In the original game, "Plan 9 from Outer Space" would be shown in mission 8 (although it is referred to in-game as "Plan 42 from Outer Space"). I am not sure why it was changed to "Teenagers from Outer Space" instead for the remake; my best guess is to fit better with the mission title, although the billboard at Turnipseed Farm still says that "Plan 42 from Outer Space" is playing. This mod restores the original movie.

To install, extract the archive to the Destroy All Humans! Install directory, being sure pakchunk99-MM08_Plan9_FullMovie.pak is copied to {Destroy All Humans! Install Directory}\DH\Content\Paks and MM08_Plan9_FullMovie.mp4 is copied to {Destroy All Humans! Install Directory}\DH\Content\Movies\MM08. If you do not wish to watch "Teenagers from Outer Space", you can delete MM08_Teenager_ReEncoded_7.mp4 to save space on your hard drive. You can also rename the movie to MM08_Teenager_ReEncoded_7.mp4 and replace the original file, if you so choose. To uninstall partially, you can simply delete pakchunk99-MM08_Plan9_FullMovie.pak and leave the movie in the movie folder. To uninstall fully, delete MM08_Plan9_FullMovie.mp4 as well.

Why the .pak file when simply renaming the movie file to MM08_Teenager_ReEncoded_7.mp4 and replacing would have worked? I chose to do it this way as it will allow a simpler/quicker way to switch between different movies once I upload more. Instead of copying larger movie files every time you want to change the movie, you simply need to copy the .pak file of the movie you want and delete the ones you don't want to watch. It also means you can keep the original movie file in tact if bandwidth is a concern or you don't want to keep a backup copy of it elsewhere. The .pak file contains a simple edit to {Destroy All Humans! Install Directory}\DH\Content\Movies\MM08\MM08_Teenager_ReEncoded_7.uasset to point to the MM08_Plan9_FullMovie.mp4 file instead of MM08_Teenager_ReEncoded_7.mp4.