However, it does not seem to work in most cases that I've found. I was super excited when it arrived, but I'm still hunting down the domains of auto-play videos and adding them to a blacklist manually.

The choices seem to be "document user gesture", "user gesture is required", "no user gesture is required", and "default". There needs to be a "never autoplay any media"

I thought I was doing something wrong when I set the flag. Thank you for confirming it really doesn't work.

Guess I should have just preached "use Firefox" like I usually do. That's what I get for trying to see things from the other side for once.

I can't think of one reason why it shouldn't be the default behavior.