I would like to report a bug and a fix (workaround) that I noticed with unity on 18.04. Videos on chromium and chrome started tearing recently for me. This is an optimus setup, so it likely won’t affect most people. The root cause is unredirected_match setting in compiz settings manager -> composite. That list by default includes common browsers and media players. However, something has changed recently w.r.t capitalisation and regex, and the strings in that list no longer actually match the respective programs. For chromium and chrome, I had to additionally add !(class=Chromium-browser) & !(class=Google-chrome) to that list (note the capital C in each case). I got these by using the grab tooltip in that field which is very useful.