+1, if your software stack decides to use CPU for video things, you’re going to have a hot lap and a drained battery. Sometimes your browser can already be using GPU for web page rendering but still uses CPU for video encode and decode.
Hardware video acceleration in a browser is somehow still a mess on Linux.
I've spent hours trying every unholy combination of browser/version/Wayland/x11/flags/command line arguments and still can't hardware decode a YouTube video on a pretty standard Intel igpu laptop. Something that should really just work out of the box.
Strange - for me, installing intel-media-driver & setting the vaapi config option in about:config (for firefox) is sufficient. I gave up trying to get it to work in Chrom{e,ium}, though.