Look at the number of complaints people post about EU cookie warning banners, which usually don't even block you from consuming the content on the page, even though they usually can be dismissed in one click. Or the number of complaints if a site puts a sign-up or logic request, dismissable in one click, that obscures any of the content.

Sure, with an extra click to play video, as opposed to an extra click to read an article, it will save annoyance on sites where the person is not there specifically because they clicked a link to see the video.

There are probably more sites where the auto-playing video is an annoyance than where it is the thing you came to the site for, and so blocking auto play is probably a net win for most people--but will they perceive it that way?

You are more likely to notice that something has annoyed you than to notice that something has not annoyed you. With blocking auto play I think a lot of people will only notice it, therefore, when it makes them do an extra click to see something they came to see. They aren't going to notice that it saved them from having to click to mute or pause some ancillary video on a page.

That doesn't mean it should not be added. It just means some care should be taken into how it is presented and configured.

I don't know about that. I would think YouTube alone easily accounts for the majority of autoplaying videos that users encounter.

Firefox only restores tabs (and thus resumes playing) once I actually select them. This sounds like a better solution for your specific problem. A drawback is it being easier to end with a significant tab graveyard. But won't be able to have it any other way once you're at four-digits open tabs...

Wall of sound I agree with. Disable that. But don't force me to click a video or gif to get it to play.