Vlc player is as old as I am using computer. It is soo useful for me that I have never used any other video player. Vlc help in playing almost all type of audio and video files, including mp3, mp4, rm, avi, etc.
It is user friendly and have very good theme. The best thing I love about vlc is that it has a snapshot option. Which can help in taking pictures from videos. It is so useful that everyone will love it. It can b downloaded using google.