When i try to save or view files in theater mode, it does not let me.
It says that “one or more players does not have and Xbox 360 hard drive” when i do.
Any help?
You need to buy a hard drive. Fitting the MM into a disc was hard enough, so using File Share and Theater will definitely not work. Sorry to break it to you 
Also, USBs won’t solve the problem, only a hard drive will. A Slim 4GB one won’t work, only something higher.