Wow. That thing was really bleeding oil in second video.
It's hard to get a feel from the pics, especially having never seen the engine. Do you have a video of it running on the dyno so show all the rear bolts and nooks and crannies so we can see?
Also, did you split the engine and tranny for the dyno? Was the bell housing clean? I swear that would have some oil somewhere.
Also, now that engine is out, can you examine shift cables to confirm they are internally dry (prob. not the problem but to rule out)?
Long shot idea- also is there any chance a connector bolt on that engine /trans type is connected to an oil source/passage and is getting pressurized oil past the threads?
I'm sure you've done all this already. I think LWJ's bmc suggestion is right on the money if it's an engine leak.
edit- I don't know what I'm looking at, but with a name like "leaky" I've got to give it a try 