Video Download Studio is the most powerful

Video Download Studio is the most powerful YouTube Video converter. It can one step download FLV videos from YouTube.com and convert to other popular videos formats; it can download and save the FLV videos on your local disk; flv video converter and it can convert FLV files on local disk to other videos formats. It supports the output format: AVI, MPEG, MP4, WMV, 3GP,

this will help you.... Use YouTube Mate.it can automatically download and convert youtube video to other video and audio formats for mobile phone, iPod, iPhone, Pocket PC, PSP, or Zune ect.

An easier way is to just get them online, flv compatible player get DVDVideoSoft's Youtube to MP3 Converter, its 100% free, no ads, simple interface, and best of all it just works. If you still want to go FLV, just use VLC Media Player.