It is a 7 x 4 brusta; a Top -Flite nylon.
In the run after the video I 'tweaked' needle and compression settings and ran it in the low 7,000's. Spent an hour or so with it. It's RPM's are not far behind a newish CS Navo Mills .75 I ran a few months ago for a mate. Impressive.
I was slightly annoyed with myself. In the video it took 4~5 flicks to start due to slight over priming. Most starts were two flick affairs.