I tried that already, didn't really help. That repo is currently deactivated on my machine, I think I had some (more) annoying problem with it (don't remember all the details), but after spending quite a few hours on this problem, I essentially gave up trying to fix it. Right now, video playback works well enough that I don't want to deal with it anymore.
And, honestly, I haven't had a Linux installation where everything related to multimedia and graphics drivers just worked flawlessly. Ubuntu, Debian, Arch and Suse all had different issues. Switching from Nvidia to AMD didn't help, either. Sometimes the flaws were minor and easy to ignore, but it has never ever worked as well as it does on Windows.
Still not a fan of pizzacakecomics. The ones that are supposed to be funny aren't, imho, and the political ones are way too heavy-handed for my taste.
I mean, don't get me wrong, I agree with the content, but for a comic that's on the reddit frontpage all the time it's an incredibly crude way of getting the point across.