About the "jerkiness" of videos: I found that mplayer does indeed play quite jerkily; the built-in media player suffers from the same problem, albeit to a lesser extent.

Most curiously, I found that when I start videos from Canola, they play a lot smoother than when started from the media player directly. This is most weird, as Canola is supposed to be nothing more than a frontend to the media player. Freezes also appear to be less frequent in Canola, adding to the weirdness.