Being more rigid would mean they don't absorb the vibrations, but they're transferred more proficiently to the end points; or points of flexation.
That's the experience I have with steel frames.
Where they tend to excel is where you don't get lots of bumps, and thus the rigidity makes more greater power transfer; such as with the depth of bike rims. Nothing makes as big a difference in the performance of bike wheels as this.
All I can say is what my personal experiences have been. I have 7 steel road bikes, not including a touring bike since that is technically not a road bike, and I have a titanium road bike, and I used to have a scandium road bike.
The harshest riding bike I had was the Scandium, while it was a racing bike the geometry was not as tight as one of my older steel racing bikes. The steel one was so tight that I had to deflate the rear 23c tire to get it to clear the seat tube, and then it took a little squashing of the tire to do so, whereas with the scandium wasn't necessary. That bike felt as if I was riding on Fred Flintstone's stone wheels, that's how bad it rode.
The most comfortable riding bike I've ever had is the titanium bike. That TI bike has deeper dish wheels than any of my other bikes, so those wheels should feel harsher riding, but I guess the TI mutes it?
Before I bought the TI bike I test-rode a lot of bikes, including riding two friends' TI bikes, and that constant factor was the TI bikes were more comfortable, so after a year of trying bikes while waiting for the right sale, I opted for a TI bike.
While none of the bikes have the same wheels, they have on occasion a couple used the same tires, because when a really good sale is found I'll buy 2 pairs, and one ends up on one bike and the other on another. I always use the same PSI in the same size tire. Since my steel road bikes are older I have swapped wheelsets between some of them and never noticed anything doing that.
I don't know about those videos, all I know is what I've experienced, not what they've experienced. I also know that my 2 friends with their TI bikes all said the same thing, the TI bikes were more comfortable to ride than any of their other bikes. I'm not trying to argue against what anyone else has said, just telling you what my experiences were.
Wag more, bark less
Location: Parañaque, Philippines
recently shifted from an Aluminum frame to a Steel Frame bike. Vibrations really do feel dampened, I only noticed it after the first ride and every time I switch back to the aluminum frame, both bikes have carbon forks too. Maybe its one of those you have to experience it for yourself even if scientific literature says otherwise