Option to hide Alt text by default when viewing media

[DukeOFprunesOriginal]

Pitch

Alt text size is very generous. Many videos or animated gifs start playing behind a wall of it. Alt text should optionally be hidden by default for those who do not wish to see it

Motivation

Everyone. It's fine to keep it on by default dor accessibility but not everyone wants or needs to see it for every image or video they view

[connyduck]

I don't like adding more options. Instead we should think about a better layout where one can (for example) easily swipe the text in or out of view.

[fsmv]

I think the simplest possible solution to this would be to make it so tapping on the screen dismisses the controls.

I noticed that videos without alt text actually already work this way, it just doesn't work when there is alt text.

In my opinion the best UX would be having a separate button in the video player controls toolbar that opens the alt text display. So it wouldn't display the alt text by default, only if you press the button.

[fsmv]

Here's a video with alt text: https://mstdn.social/@yurnidiot/113801266467466095

and a video without alt text: https://infosec.exchange/@tracketpacer/113801081640670982

Seems to me it's a bug that videos without alt text don't allow tap to dismiss @connyduck

[JDeeth]

I agree with the initial comment - alt-text should be on by default for accessibility. But for myself I'd like alt-text hidden by default on my device - could this be a situation where providing an option is worthwhile?

It wouldn't matter so much when #4854 is fixed and I can easily dismiss alt-text on videos again. (The reason I logged in and found the repo today is, if I want to show a funny video to my partner without alt-text spoiling the gag, I have to open the post in the mobile browser, which is a bit clunky)