Hello, I have the same problem on my laptop with Win7 64 bit.
I can not set the default program for opening video files nor even open them with the program I want.
When I open a .mp4 file, it opens by default with VideoLan. But I want to open it with Media Player Classic (MPC).
So I make a right click on the mp4 file -> Open With -> Browse -> I select C:\Programs\Media Player Classic\mplayerc.exe and then I click "Open" and then the MPC does not show in the programs list (it should appear in "Other Programs") section.
I have no idea how to solve this problem, can you help?
Thanks