Critical feedback up front:
Before signing up, please note that the demo video (which looked pretty, and I should have paid more attention to) when played in Chrome never successfully exited for me, i.e. the sign up elements continued to be hidden (yea, made sure it wasn't full-screen). I tried zooming in and out, pausing and playing the video. I did not investigate the DOM. A refresh restored the initial state and after signing-up I haven't revisited to play with it more.
Signing up felt a little like "hunt for the link that leads to the behavior I want". After clicking "Sign up with Facebook" at the bottom left and then telling Facebook I didn't want to give your app all of the requested permissions it aborted, but when I initiated Sign Up from the Login link at the top right, chose to use Facebook, and denied the app requested permissions, it rolled along.
I went through several of the videos and didn't see any with comments yet. I noticed that you're not linking back to the comments on the original site, and can understand there being several reasons for that, but I do wonder if there will be any integration with Twitter, Facebook, and Google+ for the comments that originate in mixy.tv? Do they get re-posted to those other services, with hashtags for Twitter, so that followers from those services are tempted to join mixy.tv and become part of the fun?
Besides crowd-sourced tagging and filtering, are there any plans to create recommendations?
Since I am not following anyone else that is using mixy.tv yet, is the "People I Follow" link supposed to show people I follow on other social networks, and will I also be able to follow people just through mixy.tv in case we're coming from different walled gardens?
One feature request would be to enable bookmarks within videos, with their own urls, so users can comment on specific points in the video, and link directly to the frame they're talking about.
Finally answering your questions:
Overall the site looks clean, the layout after signing in makes sense.
I'd like to thank your service for revealing this video to me:
http://mixy.tv/posts/ea5c3e/this-dude-loves-his-job-best-cot...
However, I need some help seeing the added value in general over my current means of finding videos. It appears the primary means to find videos is either manually searching or from the people I already follow.
By the way, is the List functionality enabled? The dialog says I created one, but then I can't find the list I created.