The phrase that really resonated with me was https://www.youtube.com/watch?v=7fvSYT7vhQY#t=404s : "When a few get something for nothing, at some point in a zero-sum game most will get nothing for something". That point may not happen anytime soon, but I think that's a very legitimate concern.
But lets say we accept its argument anyway, is it really applicable here? Would you really argue that the creation of a new cryptocurrency is a zero-sum event?
Couldn't it instead be the case that enormous new wealth is created due to the existence of a new payment infrastructure, and that the people who get something are capturing some of this new wealth?
I'm not saying Bitcoin is a sure thing by any means; just that its flawed to evaluate the wealth apparently coming from it as a zero-sum process.
It's similar for the people who "get something for nothing" by mining bitcoins: they're getting paid for making the proof-of-work chain function correctly, and for distributing the initial bitcoin supply in a way that's not based on some central authority handing out bitcoins.
Moreover, the argument that the cited video makes about criminals using the currency (i.e. "honor among thieves" doesn't exist) is fundamentally at odds with the concept of the infinitely iterated prisoner's dilemma. That's why the whole concept of "reputation" envolved (in Nature and online). Someone with 98.7% positive feedback might screw you to save $50, but doing so would not be beneficial in the long run.