You can try Cucusoft YouTube,

You can try Cucusoft YouTube, Which helps you download, convert, play and manage your favorite YouTube videos... and it's very easy to use. If you're a YouTube fan, you'll love YouTube Mate!YouTube Mate Key Functions:(1) Download YouTube video(2) Converts YouTube videos to various flv downloader video formats * Input format : YouTube FLV,SWF,AVI, DivX, XviD,RM, RMVB, MOV, MPEG, WMV . * Output format : MP4,AVI, 3GP,WMV,DivX, XviD,RM, RMVB, MOV, MPEG MP3 etc. * Portable device:iPod Classic, iPod Touch, iPod Nano, iPhone, Zune, PSP,Mobile Phone,Apple TV.flv converter (3)YouTube VideoPlayerIt supports offline play YouTube video, .flv video and .swf video.