Hi,
You can store the video file in folder and path in database, Becouse this files are huge. We always used to hire them in a special file directory.
So you can use some players with some code pattern like that
http://social.msdn.microsoft.com/Forums/en-SG/csharpgeneral/thread/ad994b06-92ad-49bb-8ab4-a36762bd4a66
There
in the youtube I think they are using Video Engine to playing multy
part videos. This is interesting with the image processing.