"Doceri is the ultimate tool for presentations and lessons. Through the Doceri Remote iPad app and Doceri Desktop software, you can control a computer (Mac or Windows), easily launch any document or application, and annotate over them at any time. You can save drawings and play them back in the future allowing even better presentations to be created from your existing PowerPoint or Keynote slideshows. If you just want to use it as a whiteboard, you can create any handwritten/drawn content on any background of your choice. And with additional room control hardware, Doceri can even be used as the remote control for projectors, DVD players, and all other audiovisual devices in your room." Doceri
You may download all of materials on this site and use them for free as long as their use is for personal, non-commercial purposes; permission has been obtained from the creators to make them available to you through this website subject to this restriction on use
The following four sites look to me to be the most likely to be helpful:
Internet Archive - Moving Images - library of free movies, films, and videos containing thousands of digital movies which range from classic full-length films, to daily alternative news broadcasts, to videos of every genre uploaded by Archive users.