I was just wondering if anyone knows if there is a way to only output sound on youtube. I have some playlists that I would like to listen to at work but I don't want to eat up all of the bandwidth.
AFAIK, that's not referring to audio/video data interlacing. It's referring to interlaced video, which is something different.
Interlaced video renders odd scanlines one frame, then even scanlines the next frame. Progressive video renders the entire frame in one go, but at half the framerate. IE, 1080p vs. 1080i