If you are using a Mac, this
[Only registered and activated users can see links. Click Here To Register...] would be the best choice.
It can automatically detect the YouTube video files from the YouTube web pages you have opened and download multiple files at a time.
As a YouTube Converter, it can batch convert YouTube videos to all other popular video/audio(AVI/MOV/MP4/MPEG/3GP/AAC/MP3...) for portable players, including blackberry.