freebeard, I don't have a video of the engine. I worked until late the night before my father's birthday, trying to get it to run. It finally did and being unbalanced, and a surprisingly powerful runner, it practically jumped off the table, so I had to hold it down. I quickly cleaned it up, and packed it in a box with wrapping paper.
I ran it once with my father, who lived 3 hours away, and that was it. Before he passed away, my brother took control of his life, and when he died grabbed all he had, including the engine, which he claimed "didn't work anyway." Meaning he didn't know anything about timing a hot air engine to make it run.
My nephew told me my brother had left it out in his garage for years and that it had rusted pretty badly. When my brother became ill, my nephew a good kid, asked if I would like the engine back, as my brother was dispersing "his" assets. I was quietly given the engine back, in bad shape. My brother passed, and now the engine sits here just as it was found. Maybe some day I will fix it up to run again.
As far as an animation goes, here's one I found with a configuration somewhat like mine, except that in mine there is no connecting pipe between the two cylinders, they are opposed through the heat sink and offset enough to just allow a small overlap where they contact each other, which becomes the air passage. The pipe dead space is eliminated increasing compression.
re. the pin size, these engines develop relatively low power and reduction of friction is very helpful, so minimally sized pins and bearings are important, as long as they are adequate in strength and stiffness. The power piston is the only one that develops any force, and that one is closest to the flywheel. The displacer piston has little comparative loading.
The crankshaft on the far side of the flywheel is substantial and set in a skate ball bearing. This allowed me to cantilever it from a single bearing, and simplified the piston to displacer crank -- making it adjustable. A feature my brother failed to appreciate.