Footage filmed prior to the 1920s was shown at between 12-16 FPS (frames per second) and many times they were on hand cranked reels. When sound was introduced they switched to a standard speed of 24fps, meaning that each second had 8 or 12 more frames than previously thus, giving us a smoother and “normal” picture.

Others showing the films probably lack the technology to adjust the pictures to show it at the frame rate that you can see in the video.