That's already available.
The videos you've watched are shown in black, and the ones you haven't aren't show in red.

oh, my bad, that´s awesome

the ability to speed up video playback speed would be life changing

I didn't see another spot to put this, but would it be possible to get subscribed thread features like 2+2? I forget to hit subscribe sometimes when I reply and then have to go looking for the responses later or forget about it entirely. It's also pretty nice having all your subscribed threads in a big list with the most recent responses first. If there is a way to do either of these things already somebody please enlighten me.

Thanks to all the RIO staff. You guys do an amazing job and it's pretty awesome having a forum like this where you get real conversations and responses. On some of those other sites I find myself reading posts from 5+ years ago more than recent stuff. I'm look forward to spending a lot more time here in 2014

Are you referring to the notifications or "my activity"? If so, not quite what I was talking about. I think something more 2+2 like would be much easier to follow.