I can provide more detailed information on or online safety depending on your goal.
Similar to game repacks, movie versions often use high-efficiency compression to reduce file sizes while maintaining quality, though this is more secondary for film than it is for games. Standard "Guide" for Using Repacked Media
Below is a detailed breakdown of what these repacks are, where to find them, and the safety considerations you should keep in mind. What is a Movies4uRip Repack?