It's just because you don't have a codec installed that will display the video element.
There are two ways to do it.
1. Download Mediainfo .. Free .. on the web, run it and try to match the codec with one from web.
2. Try a few ... Ffdshow installed will play lots of different formats. Especially mpeg4, which it could be. I think is 3gp format. You may also need Haali Media splitter.
So try these first ... (MMX version of Ffdshow) Should work fine!
These are just codecs and are only in use when you play the media. They are not programmes as such.
http://www.free-codec.../FFDShow_download.htm
http://haali.cs.msu.r.../MatroskaSplitter.exe