Thanks for doing the experiment fearn!
I wonder if there is a difference in kukri usage depending on the place and time? Perhaps the kukri was a utility blade for the Sikh/N.Indian soldier, but when a battle was to begin the next day, wouldn't he want his kukri sharpened up real good? After-all he wasn't going to be hacking at trees but a lot of unarmored men and a few armored ones? It may also be that he's doing this in the 'context' of being surrounded, and so a quick incapacitation may be better and quicker than a clean decapitiation.... after all, his own side's soldiers with their swords, maces, spears, axes, kurkis, guns, etc. can finish off a dying/crippled enemy, but a dying/crippled enemy is unlikely to kill him...
It may also be a stylistic matter. Some martial arts deem it unsafe to fully commit to a strike... and would rather win via manipulations/strategy and striking to weak targets. Perhaps it is a conservative approach?
Another thing that might affect why he is doing it that way is that he was showing manipulation techniques... and using you hand and kukri to manipulate the opponent up-close, it is very likely that in the time you take to raise your hand high to chop down, the opponent can escape and counter. Where-as transitioning right to a slice from a manipulation is quicker (but less fatal I think).
If you notice that's the same thing with the ax... there are a few chops, but when he is manipulating the opponent or the opponent's weapon, he uses a quick thrust or slice rather than rearing back and chopping. With the double axes he will entangle/disarm the opponent, then pin with one and chop with the other, or hack away with both...
Also, the video did not show the entire event, it's possible there was some more intuitive and conventional kukri use in there
