I was at my mom's recently (actually, it's a sad thing ... my stepfather passed away) and I made an interesting discovery.
You see, my mom's dad made a lot of home movies, and sometime late in his life he had a video made of the most interesting clips. When I was watching this video, I was astonished to see my mom as a young girl swinging exactly as described in the infamous swinging patent. She even used the "oval-shaped" motion described in points (3) and (4).
I aimed my Mavica at the TV screen to get an mpeg of this, but I'm not sure how to edit it: I need to remove the sound (just some dumb conversation while we were watching the video) and tiny bits of the prevous and following clips which I included in order to make sure I got the complete scene.
Can anyone help me edit this? Here it is: http://www.wiredaemons.com/forrest/prior_art.mpg. It's only a bit more than 300K. Try to ignore my stupid voice in the background.
My mom and aunt told me this must have been filmed before 1942.