Those are great videos. The dojo has them on DVD for us to borrow and watch at home, but the DVDs are all in Japanese. I didn't know it was available in English on YouTube, so that's great!!
Yes, aikido is like ballet, gymnastics and combat. I think in real fighting, only some of the techniques would be useful, but aikido isn't really about learning how to fight. The founder of aikido, named Ueshiba (the guy with the long white beard) studied lots of styles of jujutsu, which is fighting, and combined different elements to invent aikido. I guess I would say aikido is about learning how to control your own body and also to feel and be able to control your opponent. We call it "making a connection." Once you can feel your opponents balance and tension, you can move them around or throw them effortlessly. But making a connection is not easy and takes lots of practice.
The techniques in aikido (called "waza") were originally fighting techniques that would end in a broken bone or dislocated joint or intense pain, but the way they are organized and taught in the Yoshinkan curriculum, they are for teaching you how to move your body and feel your opponent. At the beginning level of aikido, most people can't make the waza work if the opponent resists. So the opponent cooperates to make the waza work. Over time and many repetitions of the waza, your body learns how to feel the opponent and you gradually begin performing the waza on the opponent rather than going through the motions with the opponent's cooperation.
Yes, I remember struggling to do a forward roll in Cub Scouts. Probably they weren't being taught very well. Paradoxically, a forward roll from a kneeling position is much harder to perform than one from a standing position. Like everything else, the key to a good roll (or "break fall" as they are called in martial arts) is in the core. (Imagine trying to roll an octagon that is loose at all the angles along the ground as opposed to a circle. Having a weak core is like having loose angles in your body.) I think when I was young I had a very, very weak core.
When I was at Swarthmore, someone told me once that the reason I couldn't generate more power in swimming was that I had a weak lower back. There was probably something to that. I think in high school I learned to compensate for a weak core by utilizing more shoulder strength. But in aikido, this is actually working against me. I constantly have to be aware to relax my shoulders and arms and maintain good posture.
I think Mike Stone was a good coach considering his level of education and the state of amateur swimming training at the time. However, if I had myself as a freshman-aged new swimmer today, I would spend a lot of time in and out of the pool strengthening the core and teaching myself to move the body as a unit with hips and shoulders locked through the core. Mike always concentrated on the shoulders and arms when he was teaching crawl stroke. At Swarthmore, Bill Boomer tried to teach us to swim from the hips. I think today, initiating crawl stroke from the core movement rather than an arm movement is the standard way of teaching, and Bill Boomer is a famous coach.
I remember the men's team used to call Boomer "Mr. Squidhands" because he was missing some fingers. There were a lot of negative dynamics on the swim team while I was there, but I think it was reaction to being in an environment where you constantly being told you were bad because of being a white male. Boomer was trying to change the way people were swimming, and there was a lot of resentment, which I think was projection from the political atmosphere of the campus. Or it's possible that the people who were good at swimming from the shoulders weren't so good swimming from the hips and didn't like it.
The knee walking, or shikko ho ("sheeko hoe"), is very, very difficult. I really can't do it at all yet. In that video, they can float across the floor because they are very well balanced. I am still performing the "Imperial AT-AT" version of shikko ho. My knees just sort of drop onto the ground like they are trying to crush Luke Skywalker's snowspeeder, and my upper body lolls forward like somebody wrapped my legs in cable. It doesn't help that I can't sit with my butt on my heels yet or that I have stiff hips. Being able to do shikko ho properly would be an accomplishment in itself.