Add addtional info for screen readers

[bjorvack]

fixes #837

Added aria-label attributes to video cards with a hidden span as fallback

[vimkat]

Still, I don't really like this solution since it feels a little bit "hacky" to add those hidden spans (remembers me of the old days with IE6) but if it helps and works reliably, I'm totally OK with it.

I just have a small question: When a screen reader supports the aria-label attribute does it also read the hidden span and therefore the description twice? Or does aria-label always replace the link text? If that is not the case, I think we should remove the aria-label when a hidden span is used to prevent that behaviour.

[bjorvack]

aria-label replaces the content of the tag as far as I know. The problem is that not all screenreaders are compatible with all the tags yet. It's a bit like mail clients and HTML 5.

Could be handy for research: https://www.powermapper.com/tests/screen-readers/labelling/a-aria-label/
Gives a great overview which attributes are supported decently

[vimkat]

Thanks for sharing this!
Alright, so I think we can merge then? Is that OK with you, @shiffman?