Use the controls located under the video to view full screen.
Even if the frame(s) show BLACK initially, click on PLAY and that will change - and you will be able to view the video.
All these videos have been taken from old VHS tapes - some of which weren't in very good condition.
The technical quality of these videos is sadly lacking, however, the content is what is important.
These old recordings show just how far technology in video recording has advanced in recent years.