Personally, I use Movavi Video Converter, it can convert videos between all formats & devices
-supports 40+ video, audio, and image file formats
* Input Video Formats: AVI (DivX, XviD, etc.), DV AVI, MP4 (Sony PSP, Apple TV, iPod, iPhone, BlackBerry, etc), WMV (including Zune, Archos and Creative Zen), ASF, 3GP, 3GP2, 3GPP, 3GPP2, QuickTime (MOV, QT), DVD, VOB, IFO, VIDEO_TS, AUDIO_TS, MPG, MPEG 1,2,4, MOD, DAT, MJPEG, VCD, SVCD, H.263. New: M2T, MTS, MKV, VRO, Flash (FLV).
* Output Video Formats: MP4 (Sony PSP, Apple TV, iPod, iPhone, BlackBerry, etc), WMV (including Zune, Archos and Creative Zen), 3GP, 3GP2, 3GPP, 3GPP2, QuickTime (MOV, QT), MPG, MPEG 1,2,4, H.263, H.264, Real Media (RM, RMVB). New: Flash (FLV).
* Output Video for Mobile Devices: iPod, iPhone, Apple TV, PSP, Zune, PDA/Pocket PC (including BlackBerry), Creative Zen, Archos, Epson media players, any cellphone.
* Output Audio Formats: MP3, WAV, WMA. New:OGG, AAC, FLAC, Monkey's Audio.
* Output Image Formats: JPEG, PNG, BMP, GIF.
If you want a try, following is a step by step guide:
http://www.flash-video-soft.com/blog/?p=176
hope it helps.