Believe it or not, YouTube is the largest legal archive of old Bollywood movies. Major production houses have realized the value of their vintage catalogs.
The platforms above usually restrict downloads to "in-app only" (you cannot move the file to a USB drive). If you need a permanent digital copy of a 1970s classic for a personal collection (backup of a DVD you own), here is the legal approach: Free Bollywood Old Movies Download
Plex is a gem in the streaming world. While known for personal media servers, Plex offers a robust "Free Movies & TV" section supported by ads (similar to old cable TV). Believe it or not, YouTube is the largest