I didn’t watch the whole video above, but he was talking about replacing the entire CRANKSET and not chainrings. But he kept saying chainring. Carefully watch that video.
The compatibility chart:
Implies the 9200 chainrings have slightly different arms than 9100. Because they are in different boxes. Let me give my experience of having cranksets in different boxes…
I have two cranksets: Ultegra 6800 and 8000, they are in different boxes on the Shimano compatibility chart. The large chainrings cannot be interchanged, because the 4 bolt arms are slightly different. Tried to do it myself and then took it to the bike shop. The young LBS manager and I spent 15 minutes before realizing the bolt arms are in slightly different locations. I have swapped the inner chainrings.
This article:
confirms what is implied by the compatibility chart:
“and while the bolt circle diameter for the chainrings is the same 110 mm, the actual location of the arms is different so there’s no mixing and matching there, either.”
which is exactly my experience with 6800 and 8000 large chainring, and is shown by the location in separate boxes in the Shimano compatibility chart.