This is the best for me http://youtubefisher.codeplex.com/. I have used it to download movies from youtube.
Download the application unto your desktop, double clikc on the application then run, copy the video address bar from youtube, paste it to the open youtube fisher, select download video and then it auto open folder to save the video in. THIS IS IMPORTANT, change the SAVE AS type to STANDARD YOUTUBE from selection dropdown.
Then click save button and watch it download.
Let me know if it helps.