This is a good demonstration of the difference between the conscious mind and and subconscious mind. He calls it "knowing vs understanding". I think my terms are more appropriate.
Even knowing how the bike works, people cannot make corrections fast enough to keep from falling. They know turning left makes the bike go right, but the conscious mind can only do one thing at a time, and not very fast. The subconscious can deal with all the tasks required to ride a bike without you having to think about it. As we see, the subconscious is trying to make the needed corrections to stay upright, but this bike makes those actions wrong, and they fall despite the conscious mind knowing the correct action to take.
Shows how you lose the ability to learn as you age.
At the Science Museum in St Louis they have piece of plastic with 2 rows of holes, you have to lace a shoestring thru the holes......looking thru an eyepiece that makes you see everything backwards and upside down, fun, I cheated, while still looking thru the eyepiece I concentrated on what I felt.
Thats relearning how to react by what you see, this guy is trying to relearn reactions to balance.
I don't think it's losing the ability to learn. You just have more repetitions to undo than a child. If you perform an act 1000 times, you can't reverse the action needed and expect to perform it without mistake unless you practice the new action at least a few hundred times, ideally another 1000 or more.
Practice does make perfect. For that set of circumstances. Everything changes. You just don't normally see things change 180º. If we did we would have no problem making the appropriate change. But that isn't the world we live in. Everything we do is based pretty much on one set of circumstances. That is an excellent example that demonstrates we do not adapt to change when it is exactly opposite of our known world. That would sure be a good tool for a lot of examples though. Even politics.
Reminds me of a quote I heard once. I can't recall who said it, but it was something like, "A person does not learn to walk as much as they learn how to not fall down."
Which is quite true since much of what the unconscious mind does it actually anticipating what is going to happen next. Anyone that has to walk up a non-standard pitch stairway or run across uneven terrain will notice this.
I recall when I was getting pistol instruction from Ernie Langdon (it's ok if you don't know who he is), but he was talking how how to walk and shoot at the same time, and he said when we walk normally, we are basically executing a controlled fall. When we shoot and walk, to minimize bounce, we should use our lead foot to pull us forward instead of falling onto it. We basically had to relearn how to walk for that portion of the class.
My opinion is that this illustrates how if you learn and practice the wrong way to do something it is very difficult to change that and learn the right way depending on how long or how old you were when learned that wrong way.