The type of videos that are good to show to cats are videos of small animals, which cats like to prey upon, moving around. Videos that show nature scenes with birds fluttering around also are good videos to show cats. Additionally, videos with mice or squirrels moving around are good.
Cats are mentally stimulated by watching the unpredictable movements of any animal that is smaller than they are. House cats typically like to stare out of windows, looking for any sign of movement, so videos that are tailor-made to engage cats are usually designed to act as windows into natural scenes. Videos that show fish swimming and darting around a fish tank are also good to show to a cat.