That’s a bit vague, what kind of videos? What codecs, what resolution and framerate? What do you mean by “choppy”: frame drops, corruption artefacts, or tearing?
I doubt PureOS is doing anything special on that front. I’m very surprised that the same videos would play smoothly in a web browser though, my experience over the years has usually been the other way around.
If you’re expecting 4K or VP9/VP10/HEVC video playback on a 2008 laptop however, I have some doubts that it would work 