Websites often associated with terms like "Mp4 Movie Guru" or Mp4Moviez provide access to massive libraries of films specifically optimized for smartphones.
For the hardcore Guru, GUI tools are too slow. FFmpeg is a command-line tool that offers granular control no other software can match. Mp4 Mobile Movies Guru
Using codecs like H.264 (MP4) to maintain watchable quality while keeping file sizes small (often 200MB–500MB for a full film). The Mp4 Mobile Movies Guru: Your Pocket-Sized Cinema