If you use an Nvidia GPU (i.e. a gaming machine or ML desktop) you'll have to force a whole bunch of settings to use it through a compatibility layer that isn't particularly stable, or accept the CPU hit of about 1 core per video file at 1080p. It's not unusable but very annoying when the fallback behaviour accidentally triggers on a laptop and your CPU ends up constantly boosting, draining the battery.

Firefox on my Intel iGPU + Nvidia dGPU likes to pretend the iGPU doesn't exist. Very annoying but I've given up on trying to get it to work on desktop. Chrome seems to do a lot better for somme reason.