I disabled that feature months ago. I've long since wondered why it was implemented in the first place. I guess lower-res videos is a good goal, but not a realistic one. I could have told Mozilla and WC3 that it would only be abused for surveillance. The advertising industry doesn't care how much of your battery, bandwidth, CPU, or RAM they use, as long as they think they can sell you their junk. As for non-advertising videos, for example entertainment videos on YouTube, most users seem to care more about resolution than battery anyway (heaven knows why, it's not as if we really need 4k on our tiny cell phone screens).