Yes, I think Safari even did so dynamically based on the mac being plugged into external power or not for a while, which I think is a nice compromise.

Apparently, there's even an API attribute that indicates whether a given codec is power efficient (https://developer.mozilla.org/en-US/docs/Web/API/MediaCapabi...), which Google must also be ignoring – not their problem, after all. (I wonder if anybody did the math of the opportunity cost of losing a few ad impressions due to the user's battery dying early vs. the incremental bandwidth cost?)