grab-tube is free online service it will help you to convert your favorite flash videos(youtube) in different video format like mp3, mp4, avi , mpg or3gp.grab-tube is very simple and easy to use. You can convert your videos through few mouse clicks. No download and sign up is required for converting videos.
If you want to convert youtube videos simple add URL of the video and select your format and click convert button. You can convert your own videos from your computer. You can upload different types of video format and convert into your favorite format and download it. The main limitation of this service is file size maximum 20MB.