Try looking at the prelinger archive, which is now hosted on archive.org. Pay attention to the copyright situation, though -- which differs heavily between countries.
There are a lot of notable films that are in the public domain in the united states because of some changes to copyright law in the US that occurred in the late 50s and early 60s -- Night of the Living Dead, the original Jim Henson version of Cube, Fritz Lang's Metropolis. But, those films are not necessarily out of copyright elsewhere (and some countries, such as Germany, have no concept of a public domain -- all works belong to the estate of their creators in perpetuity).
Thanks for the reply - that's a really fantastic resource. I've browsed through briefly and there are thousands of video. I've also found a good list of animated films in the public domain (US) so I might look for copies of some of those
I'm situated in Europe so it does indeed raise the question of copyright outside of the US. I will have to investigate and try find some legal copyright resources on the topic.
There are a lot of notable films that are in the public domain in the united states because of some changes to copyright law in the US that occurred in the late 50s and early 60s -- Night of the Living Dead, the original Jim Henson version of Cube, Fritz Lang's Metropolis. But, those films are not necessarily out of copyright elsewhere (and some countries, such as Germany, have no concept of a public domain -- all works belong to the estate of their creators in perpetuity).