Having listened to the commentary in the video it very much seems to me that this is a work of speculative fiction. What might have been if if if. No sources or real evidence given for any of the assertions made. A lot of disparate threads strung together to make a compelling story.
If there were black lancasters at Enstone then perhaps they were for SOE use over Europe or some such other more likely story?
have since had a look at some of his other YouTube videos. Looks like a nice collection of what ifs and alt fiction war stories without much to back them up.