Add the ability to view alt text for videos without relying on a screen-reader or browser extension

[daira]

Describe the Feature

Many users do not use screen readers but still find it useful to see alt text on videos. The current UI does not seem to have any means to display it, either on the app or the web UI.

Personally I have auditory processing disorder and always have captions on everything when I can; anecdotally I think this is very common (yes I know captions are not the same thing as alt text, but see below). Even users without any relevant disabilities can benefit from being able to see alt text on videos, e.g. to copy-and-paste it to text-only channels — so the UI for displaying it should support copying. In that case the user is even less likely to have specialized accessibility software (or to know how to use accessibility features built into their platform).

Describe Alternatives

Captions are supported (see also #5958), but they don't replace alt text. If you have a video and a transcript but no caption file, it's often an unreasonable amount of effort to create one, whereas adding alt text for a short video can be done in a few minutes — less if you already have the transcript.

[daira]

Another important complementary feature: #5946 (Alt Text Require should apply to videos).

For how alt text is represented in the HTML see #5418.

Increasing the alt text character limit: #4998

[pengowray]

Chiming in with additional motivation for this feature in addition to the primary benefits of accessibility and normalizing accessibility:

Least surprise (for video uploaders)

Alt text is easily viewable for images, so first time video uploaders expect their alt text to be visible for their video too, and will be surprised that their descriptive text (which may include important details such as attribution and sources) is invisible to most users, unlike alt text for images.

Great to see this project grow and develop. Hoping for a good UI for viewing video alt text. Looks like there's more discussion including specifics of implementation over at #5418 already so I'll leave it there. Cheers.

[pengowray]

To spur discussion, here's a quick mockup, with two possible user interface elements:

1. an ALT button to toggle the display the alt text — The alt text would then be displayed be in a black box covering the bottom of the video (similar to an image's alt text)
2. a "View alt text" menu item — The alt text would then be added under the video area.

Might want to have either, both, or something else.