Screen reader issues

[LukasKalbertodt]

I tested the redesign with the standard Ubuntu screen reader and identified the following issues. I am not sure which ones are just fault of the Ubuntu thing, but here we go:

• [ ] After changing the step, it just says "open studio logo" or sth like that -> No idea how to fix :/
• [ ] maybe use <time> for the cut point timestamps? -> That's not the proper element for that, I think. Unsure how to best solve this.
• [x] announce that recording statrted
• [x] source select buttons could say "share display" instead of just "display"
• [ ] Video settings, when selecting an input should say "aspect ratio 4:3" and not just "4:3"
• [x] Save locally buttons should mention which video they save
• [x] focus stays in background when overlay box active
• [x] how do screen reader users read body text (i.e. no link, button, ...)?