I got tired to buggy playback with flash player and the inability to play fullsize fullscreen video. Here is a little script designed to improve the quality of life.
What it does is first get the url of the video and then start downloading it. Once it fills the predefined buffer set in the script or the download finishes, it will start playing the video.
If the youtube-dl script from a repository doesn't work try getting it straight from here: http://rg3.github.com/youtube-dl/
For pure lazyness I also made a desktop icon where I can drag an url and it will automagically start playing the video.
Try it. It's good. :)
Setting up the script in Fedora
sudo su yum -y install youtube-dl wget -O /usr/local/bin/youtube-play http://sebastianmaki.fi/files/youtube-play chmod a+x /usr/local/bin/youtube-play