WOW ! Excellent build cheapo45 and excellent kit (and more) from Little Locos.
The video is great and the engine has a bizarre sound with the hit and miss cycle. The drop cloth background in the video and for the detail pictures is helpful. (My workbench looks like yours, he he, but who cares?)
I have always more-or-less glanced over the hit and miss engines because I didn't really understand them and never wanted to take the time to learn. This helps a lot, but I still don't really understand them......maybe eventually.