That makes sense - thank you @maki !
Filip mentioned that a Tx could be taken away from the mempool by the sender if it was in a stale block, to stop a payment for example. I canât find his original text but this is how i understood it - how could one do this and what is the liklihood of it being successful ?
@maki Filip said:
You are correct, the tx will go back to the mempool. What can happen however is that a payment that you have received could be taken away from you. Letâs say youâre an online store and you sell digital goods. If you get a tx sent to you, you send the product to the customer, then the tx happens to be in a stale block.
If the sender has bad intent and removed the tx from the mempool, you as a receiver of crypto have now lost your money. But this almost never happens of course. But this is one of the reasons you should wait 6 confirmations.
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In case the tx gets dropped back to the mempool (or just is in the mempool), the sender can broadcast a new tx using the same UTXOs using a higher fee, insuring the tx will be confirmed first, thus invalidating the original tx. 
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This sounds complicated for an average user. Would a wallet perform this task for you? Or would a transaction just not confirm for a long time and then come back to you ? @Alko89
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Some wallets have a replace by fee option in case a tx is stuck in the mempool for a long time. But it wouldnât do this for you, you still have to initiate the tx yourself.
You can also wait for about 2 weeks by which time nodes will start dropping the tx from the mempool themselves.
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Cool, this is starting to make sense. My final question is that if you want to send someone money could it be that the fee is not high enough and they donât receive the funds for 2 weeks? Or would they receive the funds and then two weeks later the funds are returned to you (the sender) ? If you needed the receiver to receive the money straight away - would you need to put a high enough fee on the transaction in order for it to go through quick enough ? say you were buying a coffee in a cafe for example
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If there is a congestion and want to have your tx confirmed in a timely manner then you have to set a high enough fee for it to get through.
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Hey @filip,
Lets say I send money to myself before an update, what if during a hard fork, my transaction gets picked by both the forks, wonât it give me double the amount in two separate version of the fork blockchain ?
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Hey FilipâŚ
As per my understanding, once u write the first lineâŚâthat hard forks make previously invalid blocks validâ. This statement is very confusing. It is understood if u say that â that hard forks make previously valid blocks invalidâ. As per the example, previous 1mb blocks would become invalid after the update as 2mb blocks become valid now. After this update, all 1mb blockâs txs would be going back to mempool.
Another confusion is âHow much time does it take to propagate an updateâ to 100% miners? What I believe that if someone is seriously mining then why a miner would go offline to miss an update. And whenever there is an update, all the online miners should receive it in real time simultaneously disregard to their geographical locations as update release is via internet.
And third confusion is , if all the txs of an invalid block go back to the mempool, then how come the Bitcoin Cash, Bitcoin gold, Bitcoin diamond etc. coins come in to the existence after a hard fork?
Please, I may sound foolish but I am seriously not getting it even after watching the video twice. Kindly help me here. Thanks
After watching second video, I got more confused. Expansion/contraction is fine but rest of the explanation has been over the head transmission. 
Yes, after the fork two versions with the same history exist.
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A miner would update its blocks once it gets backed online based on the chain he is on so it doesnât matter if it is during the update.
Because they are separate blockchains, they have nothing to do with Bitcoin anymore except a common history. They work with their own rules.
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After going through the article from Binance academy, things got little bit clear. But still I donât feel confident, Anyways, I am moving ahead, may be after few sessions, I develop an understanding towards this topic. Just wish me luck. 
Thanks Alko89âŚI am coming close to understand forks after your explanation.
Hi Alko,
Thanks for the reply but it doesnât answer my question.
Could you please give it another look, "Lets say I send money to myself before an update, what if during a hard fork, my transaction gets picked by two miners using different version of the forks , wonât it give me double the amount in two separate version of the blockchain?"
when a Bitcoin fork occurs, anyone holding any amount of bitcoins will also get the same amount of the new currency. This situation doesnât automatically happen but you need to claim these coins. And each coin has a different claiming mechanism. So you will have two separate currencies,
it doesnât mean you have the same amount of bitcoin in the new version of blockchain if that makes sense.
.
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So ⌠51% percents from all the nodes that operate my brain network understood the videos but the other part are still struggling and those are the nodes that try to makes sense of everything 
I am just going to lay out my version of what I understood in as little words as possible
Accidental forks we good on that, makes sense and it was touched by Ivan on previous videos in different ways, got that.
Hard forks : A change in rules is requested, ex: increase the size of the block, rule is accepted by only 55% of network participants, this 55% will continue accepting the old size rule along with the new, the other 45% only accepts the old size. (if the agreement on the rules does not reach 100%)This eventually leads to a SPLIT of the original chain leading to two different chains that play by their own set of rules, 1st one is more inclusive and accepts smaller sizes but the second one is more conservative and only plays by the old rules. And they continue on doing their own thing separately, this leading to all these variants of BTC as BTC cash, gold and so on. Like ⌠is this what happens ? basically one common âancestorâ but at one point a separation happens over a disagreement or a total change of rules and the split results in 2 new âcommunitiesâ one more inclusive than the other ? Iâm trying to make sense of it all by feeding my mind the information in comparison to an analogy that is easier to understand.
Soft Forks : I am going to continue with the âcommunityâ based analogy but in the case of the soft fork we are talking of a change in rule but that change includes the version of truth from both communities. Thus no split will happen as they will eventually reach an agreement that this change is beneficial to them and makes them stronger as a community.
Sorry if the analogy is not one of the best but this is what I could come up for now⌠Iâm confident enough that Iâve got the gist of it but Iâm only looking for confirmation to have my doubting part of the brain agree on the version of truth 
*Note : Iâll give you guys some constructive feedback and I mean this with the best intentions in mind. @filip Iâll point out two elements that I personally think made the videos a bit harder to understand (compared to @Ivan 's) 1st would be the minimised video of yourself, there was a lot of mouse movement and drawing (which made me loose focus at times) and the human element was missing, having a âfaceâ to connect with by looking at facial expressions and gestures helps a lot and I mean a lot, there is more connection and it helps with the relaxed state that a student needs to be in order to grasp the information better. And 2nd is the use of analogyâs, maybe and explanation that relates to some real life events would help newbies, like myself. I give you this constructive criticism from an experience of training and leading large teams for over 6 years and myself had to learn and better myself in training others and so I adopted small things that helped me teach and train my team to perform better. (there has too be more of a story telling)
Sorry if this is a long post but I had to express myself, hope my good intentions did not offend anyone. 
Is it possible for a node to receive new blocks at the same time from competing miners? What happens when there is a collision of this sort? If so, how are âcollisionsâ resolved?
Thank you in advance.
Thanks for the reply.