Hulu, Twitch, those are two examples.
By support, do you mean the ability to add them to wikis? You would need to ask staff. As far as I can tell, they haven't been on the list of supported sites for at least a year now.
Yeah, not sure why they no longer support them it. Also, the Flickr images are broken. Whenever I search something from there, it just says 0 results.
Well, for the videos, use Special:Contact/general. Assuming Flickr is supposed to be supported (I never really payed attention to the online host options), use Special:Contact/bug. I would be interested to know what they say, if you don't mind sharing.