I have been using this freeware: Kigo Video Converter Free for Mac(http://www.kigo-video-converter.com/free-video-converter-mac/index.html). It can convert between MP4, FLV, MOV, etc. U can go to a try, hope to help you, many thanks!
i use ultra video converter. http://www.funadvice.com/photos/putdvdmoviecomputerburnipodtouch
but if you dont want to pay for the converter then nchsoftware.com do a pretty good one called prism video converter.
If you need to convert AVI to MP4, this free program can work for you: http://funadvice.com/r/15f7nfnlfio
www. xilisoft.com/mp4-converter .html (delete the spaces)
yeh, I have tried kigo video convert, it's amazing!