which zip files did you download?
I use the flashvideobundle/TCPMP combination to play my youtube videos. I don't go on youtube often enough to warrant its own program to install, but it's useful to have when I want to look up the occasional video. For flashvideobundle, you just install the cab, go to
www.youtube.com (make sure you are on the full sized site), search whatever you want to watch and click on the picture. It'll pop up a menu with one of the options being "Play Video". If your TCPMP is set up correctly (i.e. default media player for major filetypes including .flv) it should take everything from there.