Thank you, that makes perfect sense! I have one more question! So at the end Booker says the only way to stop all this from happening is to kill Comstock at his birth which means Booker would have to die before making the decision about whether to be reborn or not. So he lets Elizabeth drown him to prevent Comstock from ever happening? This confuses me because there are infinite dimensions where Comstock has happened and where he hasn't already. How can drowning this one Booker in this one random world seemingly created by Elizabeth to relive Booker's memory, solve anything? Won't there still be other dimensions with other Bookers and Comstocks? Also, how can the Booker we are playing as have any impact on whether Comstock is "born" or not since, at least from what I understand, we are playing as a version of Booker that rejected his rebirth after Wounded Knee. What would our version of Booker's death make possible? Furthermore, if Comstock was never "born" wouldn't that change the entire lives/realities of the Luteces as well as Elizabeth/Anna? As well as all the people who lived in Columbia?
Ok so big disclaimer, this is all my interpretation of events and in no way definitive.
After the destruction of the Siphon, Elizabeth becomes full control of her powers, effectively becoming a god. After taking Booker to Rapture they pass through the lighthouse door and everything from that point on takes place in manufactured pocket dimensions that she is using to help explain everything that happened. Nothing and no one they see is real, outside of possibly the Luteces that are rowing the boat because they are the only ones to acknowledge Elizabeth's presence and the whole situation.
This culminates in the final reveal at the return to the "baptism", which still is not taking place in any sort of actual reality. The multiple Elizabeths (note "our" Elizabeth, the one with the Bird or Cage, is not there) confront Booker with the final revelation that he is Comstock. Whether his permission/acceptance is necessary at this point or simply for her own satisfaction, once Booker comes to terms with the truth she "drowns" him, which is actually her severing the accepts baptism/becomes Comstock timeline from reality.
Remember that the multiverse of Infinite deals in variables and constants. Parallel dimensions only occur when a specific event has a variable outcome. For example, when Booker flips the coin there is no dimensional split because the result is always heads. The events of Infinite can be traced back to one split, where Booker accepts or rejects baptism. By turning this occurrence from a variable to a constant, Elizabeth prevents Comstock from ever being born. As a result, Anna is never kidnapped and all the Elizabeths start to disappear from existence. Whether or not the ur-Elizabeth survives this is questionable, as at this point she seems to be no longer bound by causality.
So yes, everything changes, or rather doesn't change, for everyone involved. The versions of people that existed along the Comstock timeline all disappear from reality. The versions that existed along the Booker timeline remain unaffected.
It's a well made video but the problem, at least for me, is that it goes on too long and delves into history lesson. It's less important that Mario has had a damsel in distress for 20 years than the fact that it's still happening in video games, which she says she goes into next episode. I really feel like she should have combined this episode with what I assume will be next and get to her conclusions quicker.
Also, realistically, I'd much rather her take on something like the new Tomb Raider, which came out this week!, than her take on remaking Double Dragon or Karateka and keeping the content the same.