I was using uploadify for uploading admin submitted videos. Now we are having mp4 videos which doesn't get displayed in Firefox. I know it is told to give an ogg version as well, but I cannot ask users to convert videos in two formats and then upload etc. - that won't be userfriendly.
Hence, asking what people are using as a solution to this problem. Thanks for your time.
FFMPEG is the solution. After uploading, use ffmpeg to convert the mp4 videos to webm (for firefox) and ogg (if you feel necessary, for compatibility with older versions of firefox) in the server.