Twitch is to start selling video games, effectively using streaming sessions as a commercial. The people playing the games online will get a cut of the sales from their stream.

It’s an idea that makes so much sense, it’s surprising it hasn’t been done before. People watching Twitch are inherently interested in gaming, while seeing a video of somebody playing and enjoying the game could be far more effective as a promotional tool than box art or print ads.

As shown in the mock-up above, there’ll be a “Buy Now” button added below the video window when somebody is playing a game that Twitch has signed a deal to distribute. 70 percent of the price will go to the game distributor, 25 percent to Twitch and five percent to the Twitch user playing the game. However, the users will need to opt in to the program before they become eligible to receive this share.

If the game is selling for more than $4.99, the buyer will also get a virtual Twitch Crate with digital goodies such as emoji and Bits, a virtual currency used to buy animated GIFs to use in Twitch’s chat feeds.

The Verge notes a potential side-effect of the deal: there’ll now be a much bigger incentive for games makers to pay the most prominent Twitch streamers to play their games.