Observations halfway through the video:

I got 5, but from the fact that 50 reversed is 5, 50 - 5 = 45

But anyways 5 was just like what Prof. Loh got

Coincidence? **I THINK NOT**

Also

Prof. Loh's guess and check numbers

74 - 47 = 27

84 - 48 = 36

92 - 29 = 63

83 - 38 = 45

All multiples of 9, and it seems that the higher number you start with, the higher your sum. It is just a general trend, of course, as you can see 84 - 48 was a lot lower than 83 - 38.

But...

Coincidence? **I THINK NOT**

And as it turns out... I thought right

Coincidence?