This probably isn't precisely what you're looking for, but some of it can be fascinating.
It's the Internet Archive
, home of the Wayback Machine. There are a zillion movies, a lot of them awful, free to download at different rates or for streaming.
They range from pre-1910s silents — the aftermath of the San Francisco earthquake — and 1910s and '20s silent-movie features — the original 20,000 Leagues Under the Sea — to cartoons and old two-colour features and more modern Technicolor flicks.
And who could forget Ford's how-to-sell-cars movie, starring Beaver Cleaver's father?
The original DOA is there, and a bunch of other films that still show up on TV.
has free movies, as well.