Here is another way of thinking about the trick...
For 54 x 11, set out a column addition with 54 as the first number to add.
Write 54 again, below the first 54, but this time line up the 4 in the ones column of the second 54 with the 5 in the tens column of the first 54.
Add them together:
What digit is missing from the ones column of the second number in the sum?
What do you know about numbers that end in that digit?
Why is this the same mathematically as the trick in the video?