That is why I love The Best of YouTube. They have distilled YouTube down to just over 1,000 top videos and they have a voting system to give you an idea of how other users rate the videos.
Obviously, not all the videos will appeal to everyone, but I've been working my way though the site and I've found very few real stinkers. I judge this site to be a quality time waster and well worth your video watching attention.
Here are a few of my favorites so far:
What is the Large Hadron Collider (LHC)?
Slightly Different Gymnastics Routine
