This is going to be a little tricky, but doable. Rick Prelinger has amassed a collection of public domain documentary films Navigating it has gotten a bit more difficult lately, but it looks as if you can search by using dates as keywords. See if you can find interesting materials in the year of your timeline. If you can, download it/them to your xroads folder, probably in MP3 format if it's available. The lab machines have QuickTime Pro mounted on them. Open the film(s) in QT, save as a self contained file with a .mov suffix; open that file and export it as Movie to Hinted Movie.
To house your clip,create a small site which should include pertinent information about the film, director, studio, actors, date of release, plus a brief description of the film -- no more than 250 words. We should discuss the format of the sites so they're uniform across the group.
To see the sort of thing that I find interesting, e.g., go to the site, drill down to 'moving images' and search for 1930; then find the film "Master Hands," then search for the title to see all the parts. Another is 'From Dawn to Sunset.'
Please check with me before you download your film(s); we've already got .mov versions of some of the more notable stuff and there's no need to waste your time.