Changing m4v video format to flv, mpeg, avi, wmv or mp4, which free website actually works?

I’ve been trying for days websites like Zamzar to change this less than 2 minutes video in m4v format to any of these, flv, mpeg, avi, wmv or mp4 format. Still no luck and I need to download the video badly to a website which accepts only those formats mentioned.

I took the video from a Nikon Coolpix camera bought 3 years ago and downloaded it to ( Mac OSX 10.5.8 ) iPhoto then went to iMovie and imported it. It comes out in m4v format when I try to download it from the website I needed it transferred. Your help would be a life saver! Thanks! : )