So, it happens with any video, if I play them for long enough. As for the specific codecs and framerates, I have no idea, actually, about that sort of thing. I can tell you that it happens regardless of format (I’ve tried .ogv, .mkv, .mp4, m4v, etc.), media player (vlc or totem), or size (a few megabytes up to several gigabytes), and it won’t go back to normal until a full reboot.
If you happen to have access to a Librebooted X200, you could try it yourself; just install PureOS (and make sure that all the packages are up-to-date), download a video that’s fairly long (about 2-3 hours, or so), or several shorter videos, and start watching; it’ll start out playing normally, but then the video will eventually start to play like it’s shot in slow-motion, and skipping frames.