Re difficulty, certainly correct for such as I. But both Chet & Mark studied hard core jazz theory before this collaboration, and the live YouTube vid shows just how relaxed they appeared rolling out those scales and licks.
I also agree about the Chet v MK solos, that's why we all love Mark, his often restrained licks (especially the ones that flow through two or more chords - my favourite example of this is the amazing solo in Once upon a Time in the West, where the average listener barely discerns any chord changes but the notes roll like gentle waves over them)
Chet was a little more 'old school' fast triplet scales, modes, without total emotional impact (as Bruce Lee once explained it lol)!
You're vid is amazing mate, I don't want to take anything away from it by over analysing, amazing work - very enjoyable. Do you play in a band, or get out and perform?