There's a similar thing I investigated a while back: Flattr. Content creators could put Flattr buttons on their websites, and Flattr users would pay a set monthly fee ($5 was the default, I think) to use the system. When you liked a piece of content, you would 'Flattr' it by clicking the button; at the end of the month, your $5 (minus handling charge, of course) would be split between the sites you'd Flattr'd based on the number of Flattrs. So, if I clicked a Flattr button on three Bit-Tech articles and two Eurogamer articles, Bit-Tech would get $3 and Eurogamer would get $2. If I clicked on five hundred individual websites, each website would get $0.01 - and so on and so forth. The idea was to split the money away from the act of 'liking' something: the content creators still get cash, but because you're not actively spending money to Flattr something (i.e. you can Flattr one website or a million websites in a given month, and you'll still only be paying $5) you were more likely to do it. Neat idea, but I don't think it was ever terribly successful. Well, firstly Twitch wouldn't get any of that money - so that's Problem The First. Problem The Second is that it takes you away from the stream: you have to stop watching to donate, and if you want to donate the chances are you don't want to stop watching. By the time you *do* want to stop watching, you might not want to donate any more. See above, though, for reasons why asking someone for a 'Cheer' (or a 'Flattr') is vastly more likely to succeed than asking for Actual Cash Monies.
This prevents charge-backs through PayPal, costing the streamer and a major financial headache. It's a major issue and a solution has been wanted for a long time. It also means that the payments would come through with other Twitch earnings, all in one payment. This makes Taxes considerably simpler to work out. This cannot be reversed as Twitch now sits between the end-sure and the streamer. The customer gets their product (cheers) and cannot initiate a charge-back as they received what they purchased.
As Fantus said, chargebacks are a very real problem for people who stream as their main job. PayPal is very outdated and still classes 'tips' under goods sold, which means people can claim all the money back saying they are dissatisfied. Which isn't really right when you've just gifted the money and not bought a product. I love Twitch, but they really need to work on this. One thing that's raising eyebrows is that Twitch take a cut from the purchaser and then again when the eligible streamer receives the Bits.
I can't believe I managed to sit through that entire video... Anyway, it seems Cheer is not being taken well by a lot of people. Not only Twitch taking a cut twice, but the biggest thing seems to be how much you have to filter now to make chat readable! It's really, REALLY spammy I'm sure it will calm down, but it has not improved the chat experience at all.
Further clarification today confirms that this isn't the case. They're only take anything at the purchase point, streamers get everything given to them after that (100bits=$1). The cut is bigger than PayPal would take but, as has been mentioned, this keeps everything within the Twitch system and protections.
Good that they're providing more information. Though I can't help but feel every single time Twitch introduce a new feature they end up apologising for not giving any warning it was coming and that they'll learn from that in the future... I'm in the Twitch Research Power Group thingy (they sent the invite to one of my bots ) and we had no heads up about it at all. Although I do wonder if they're hinting in that article that we might receive bits now in the Sweepstakes. Currently you fill in polls and get put into a raffle to win Twitch 'swag', but (and this isn't really shown clearly, they confirmed it on the Twitch reddit) it's only open to US because of the monetary value