Too many primary source videos to list, but a worthwhile visit if you have the time to find raw footage to accompany any 20th century US History lesson
This 2 minute video captures the clearing of Bonus Army veterans from Anacostia Flats in Washington DC., It is important to tell students that these are World War I veterans being evicted from their shack/tent city built in Washington following their march to get the pension money that was owed to them by the federal government
AT&T Archives: Introduction to the Dial Telephone - YouTube
Although older teachers like to joke about students, and their younger teaching colleagues, not knowing how a rotary phone worked, there was a time when no one knew how to use it. when it was invented. This Bell Telephone System video taught people how to use the dial when in was introduced in 1936