A statement saying the movie was slowed down by 10x would be included in the explanation or legend. For slow processes, you can drop frames during digitizing and speed up the rate of playback with an editing program. These movies still look good played back at very slow frame rates in large windows. Use a still image with or without sound if it does the job. The rate of the data transfer is called the data rate.
Movies play best if the computer being used can play back as fast as the data rate of the movie.
If the computer maximum data rate is much slower than the movie data rate, frames are dropped unevenly. The movie may play 10 consecutive frames and skip 30 frames if it gets behind. The result is sputtering pictures and sound that breaks up. Good digital movies have an even data rate. This rate is called the frame rate of the movie.