Is that actually a bad thing?

I have no idea about video playback controls, but in every other instance I've noticed where sites implement their own custom versions of browser controls, it's been absolutely terrible.

Custom scrollbars, or lack thereof. Custom drop-down lists, which never support keyboard input properly. And so on.

And even if I'm wrong, and custom video playback controls are somehow desirable, why should they be supported for any event except onclick?

obvious example would be articles with scrolling effects (eg. https://www.newyorker.com/magazine/2021/12/06/the-secretive-...), and need to autoplay videos when they scroll into view. That said, even if you restricted it to onclick, I don't imagine it's too hard for a page to receive a stray click (eg. if you're randomly selecting stuff) to trigger playback.

That is not a legitimate example of a good thing. That's a legitimate example of something that shouldn't be a thing

It is imho very valid to experiment with new forms of multimedia mixed stories.

And just because some people abuse features that enable this we should not try to stifle innovative ideas as a whole imho.

I just don't use sites that do this anymore. I mean the abusal part.