Here are some links to places where you might be able to find some of these movies on video and DVD:
When you click on the title and go to the entry from the Internet Movie Database, there is information on if the film is available for purchase from Amazon. Look on the right side of the page, which will have information on which formats the video is available in, as well as the musical soundtrack.
If you are looking for videos in the European PAL format, also try the UK Amazon site.
This online store sometimes has harder to find items. For a while they were the exclusive seller of Mary Queen of Scots.
Good source for silent and early motion pictures on video