Quite amazing how little work and new spare parts was required to make this engine run again, but he took a big chance on the main bearing(s) journal condition.
I myself would have inspected the main bearing journals for corrosion, been as there was a significant amount of water in the sump when he first got the engine.
Judging by how the engine is hunting when it first starts, it looks like the governor mechanism could do with a little fine tuning.
He must also be using A/F spanners instead of Whitworth spanners, see how loose the open ended spanner is on the nut, when he tightens the 3/4" BSW cylinder head nuts.