I can then compute the differences between images and then sum those differences into a 'long exposure'. If I set a threshold correctly in my code, the motion of the bees just pops out.
Bees move very fast so this is a short 2 second exposure running at 30 Hz. So this is the sum of a the differences between 60 contiguous video frames, thresholded so only the largest motions (the bees) shows up: