The best all around media player is VLC media player by far. It lets you watch any video type.. even if only part of the video is downloaded or if it is corrupted you are still able to watch.
It lets you watch dvds has many options for deinterlacing etc. All you need to do is make sure you have all the codecs you need decode the different video types and voila.
It is cross platform and open source so lots of people are working together to make it better!
You can also use it to host your own video streaming or to watch other video streams.
You can find out more and download it here:
http://www.videolan.org/vlc/ 
