As long as it's obvious that what you're doing is a parody and there is absolutely NO MONEY
to be made (that goes for soliticing donation requests for production costs or website expenses), you should be relatively safe under U.S. Copyright law for "Fair Use" and "Parody".http://www.writersrelief.com/blog/2011/03/parody-law-for-writers-how-to-protect-your-legal-right-to-spoof/
If you adhere to the above conditions, the worst you may expect is a "Cease and Desist" from any one of the copyright holders (Paramount, Fox, music publishers.)
If you make any kind of money from the video and
you didn't secure the proper copyright permissions, expect a lawsuit.