I'm on a fairly recent Macbook. Youtube flash videos easily suck up 75% of my CPU, which is killer when on battery. With this script, the *same video* takes around 1% CPU in the MP4 / Quicktime plugin version. The script works really well in Safari with GreaseKit; highly recommended!

Mplayer uses less CPU, and videos are a lot smoother, especially when going full screen or in HD, than with Flash. This script will forever enhance my Youtube viewing experience (or at least until they start using HTML 5 <video> tags). It has some extra features too like automatically going to the highest quality and being able to easily download the videos. I highly recommend this script to anyone, especially people who use Linux.</video>

For me YouTube Perfect is a true Hidden Champion. While I was so bored whenever my Laptop fans fired up when showing Flash videos now - with YouTube Perfect - everything stays calm avoiding Flash and using my video player.

Love the script, but new bugs have suddenly appeared:

*drop-down options menu no longer accessible;

* videos no longer load in HD. The function is available, but it must be manually selected.