Mashup films can be broken down into several predominant styles and approaches. These categories, are: word associated mashups, which like "DJ Danger Mouse's Grey Album "unite two different source materials by a pun or joke found in the name; and overdubbing mashups, which use the images from a film and replaces the soundtrack with new dialogue or dialogue from another work, which undermines the original narrative. The producers of such genere are called "Re-cutters"
"Reality Mashups - Using only found footage from everyday life (all imagery from popular culture, movies, politics, cartoons, video clips and existing documentaries cannot be used) and mash them together to provide something creative about any appropriate topic.
"Sequel Movie Trailer Recut" - Choose a movie that does not have any sequels. Create a fictional movie trailer for a sequel to this film. For example "Titanic 2 - The Surface" on YouTube.com. You can use footage from any source to create your work.
A good example of this is "Titanic 2 - Jack's Back" - http://www.totalrecut.com/totalrecutgallerydetail.php?videoid=1
"60 Second Subvertisement" - Choose a product. Find ads that this company has made in the past. Recut the ads into a new ad that subverts the original message. You may use footage from other sources and minimal original work. Maximum length is 60 seconds.
Some exceptional word associated mashups include "Must Love Jaws", a combination of the romantic comedy Must Love Dogs and Jaws in which music cues and humorous scenes turn visual source material from Jaws into a story about a man who falls in love with a shark.
8Â½ Mile is a mashup of Fellini's film 8 1/2 and Curtis Hanson's 8 Mile.
One of the best received mashups to date is word-associated: "10 Things I Hate About Commandments", from 10 Things I Hate About You and The 10 Commandments.