The quality varies - most of my subscriptions now are in 1080, and one of them is 1080p60 (very nice). The 4k content only works for me Tuesday-Thursday-ish (too much network congestion, it seems, despite being on Time Warner's new 100mb service).

What I'd like is the option to filter by video length. Anything under 45 seconds seems to be posted by teenagers, and I just don't care.

You might have a weak link somewhere in your connection to YouTube. ISPs have been known to throttle YouTube to reduce bandwidth costs.

Almost all of the content I find on YouTube is 1080P, and some of it is running at 60FPS.