Know your Android phone
Download & save you tube videos directly from android
Now, you can download videos from android phone and can them in flv or in mp3 format.
This can be done using Tubemate application.
Note that this app is not available in android market.
Download it from the following link:
After installing the app, search for any video. When you click on the play button to play the video, it will ask whether to play the video or download it. You can select the download option and save it on your phone either in flv or mp3 format.