He’s doing a number of ‘double cuts’ (starting to remind me of another recent thread!)
It’s most clear, where you can clearly see exactly the fingers he’s using, at 1:30.
It’s a melody note A, cut with C and B in sequence:
xxo ooo
oxo ooo
xxo ooo
xoo ooo
xxo ooo
He does them on the lower hand too. I’m not sure which fingers he uses, but I use the same fingering I use on the upper hand, just with the lower hand.
You can hear these at 0:32, 1:02, 1:30, a cluster of them around 1:34, and I think again at 1:44. Sometimes it’s hard to hear and you need to be able to see somebody’s fingers to be sure, but it sounds like a doublecut to me at 1:44, the same technique he’s using on various other notes.
Obviously for A you only have two digits available! But for E (the note in question at 1:44) it can be done in several ways.
I use the same finger action that I use for A, for E:
xxx xxo
xxx oxo
xxx xxo
xxx xoo
xxx xxo
but his sounds more crisp, as if higher notes are used. You can sure do things like
xxx xxo
xxo xxo
xxx xxo
xxx oxo
xxx xxo
or any other sequence of two cuts you like, whichever sound right on your particular whistle. On high E some cuts sound muddy on some whistles.
At 1:29, just before the double-cut at 1:30, he’s doing an ‘upper mordent’ or pralltriller.
BTW it’s odd/interesting that he plays the repeated high Bs with no ornamentation at all, given the somewhat florid ornamentation he’s using elsewhere. I learned this tune, back 35 year ago, from a traditional player, who played various rolls in that high B passage, making the tune sound more like a traditional tune and less like an orchestral tune.
To him that passage with the high Bs is more or less equivalent to the next passage which can be thought of as a series of repeated high As, just that the latter are handled with turns and ornaments and such. He did the same with the B passage, in other words conceiving that part as being
BBB B2AG
AAA A2GF#
both lines being equally subject to his full repertoire of variations and ornaments.