at 10:57 you can see the judder ring inside one of the larger diameter friction plates. Then at 11:06 you see the channel where the judder ring carved a groove in one of the steel plates.
You should also check out
@Protonhound's posts #178 and #180 which show the ring. He has some YouTubes, as well. As far as I know, he was the first to tear into the 2.5 clutch, for which he should be credited. It seems very few riders are willing to do much of their own work on these bikes. When I had the Roadster there was a ton of wisdom from members here who thought nothing of maintaining or modifying their bikes.