Vulgarity warning!
I wanted to make a GIF of one bit of this conversation (found here: http://i.imgur.com/ikXq84k.gifv). The cleanest copy of this I could find was 400x304. I manged to bring it up to 500x380 without too much degradation. While I was at it, I corrected some of the color.
A purely enhanced version of this clip can be found at https://www.youtube.com/watch?v=g4d1r...
How did I do it? A combination of Detail-preserving Upscale, Unsharp Mask and color correction effects in After Effects. I won't be handing the exact settings out because those won't do you any good - they should be tuned for each source video. Copying mine for this video would just lead you into moments of frustration rather than let you experiment from the get go.