This is the oddest component. In standard file-sharing syntax, one does not "install" a video file—you open or play it. However, the term likely arises from:

: Locking your files and demanding payment.

The results take the user to a bare-bones page showing filenames, file sizes, and download links. Because these directories lack advertisements and streaming players, some users seek them out for fast, direct downloads. The Danger of "Install" in Movie Searches

The word "install" is a smoking gun. Cybercriminals know that users searching for this phrase are often less technical. They create fake "media players" or "MKV codec installers" that, once executed, will:

If you're looking for an MKV file of the movie "3 Idiots", I assume you have already obtained a copy of the movie. If not, you can try searching online for a legitimate source, such as: