We've asked YouTube for comment.

This could just be a test. If it represents a planned launch, though, it won't be surprising. With more top Twitch streamers heading to YouTube, there will be more people wanting to back their favorite broadcasters. This would give fans a way to offer support at no extra charge if they already subscribe to Premium -- and, of course, help YouTube boost Premium subscriptions in the process.

Update 1/27 11AM ET: YouTube tells Engadget this was an internal test that inadvertently rolled out to external users. It's not guaranteed an official launch, then, but it still wouldn't be a shocking move.