So, now that Art's had his Youtube rant, I'll have one of mine. Why the fuck are random videos showing up in my History? Actually, they're not completely random; if an embedded video shows up on my tumblr dash, it ends up in my History now, even if the video was never played. Also, I'm pretty sure some video thumbnails that show up at the end of a video are being put there, too. My History is for videos I've fucking watched, not unplayed videos that happened to randomly appear on my screen.
Edit: Guh, nevermind. It turns out the problem was part of an extension I'm using.