I thought it was interesting when he took apart the gyro and messed with it's friction ability and then gyro could no longer spin.
In figure skating, when a skater prepares for a spin, the skater takes a wide inside back edge with a slight crossover maneuver (crossover at the millisecond point of entering the spin-going backwards usually) before the intended leg reaches into the beginning part of the spin. Usually the left leg for a right handed skater becomes stationary and centered. In order for the spin to work effectively, (here's the physics; you chose the nerd factor ), during the moment the skater swings into the spin, for an upright crossover spin, the skater goes from open arms to bringing in the arms tightly to the chest (or overhead). The faster the arms are brought in, the faster the spin. This then increases the spinning speed exponentially, when the skater's spin is stable and centered (traveling- which means, the skaters spin is not centered and is "traveling" away from the origin of the spin and skater is actually moving inches in another direction; points off for traveling a novice no-no) to finalize the spin, the skater would cross over one boot over the spinning boot and voila....you have a crossover spin. Here's another physics part ~ if while the skater is spinning and the skater changes positions, which during competition skaters have requirements to meet to complete several different spin types during the same spin session ( e.g. lay-back, broken-leg, camel, sit-spin etc.), when the skater breaks the momentum of one spin and goes to the other, watch the arm movement. The arms open and change the direction and spin speed slightly before resuming the new position for the spin and the momentum begins over again while the skater is in a different spinning position. The physics in jumps is also interesting on how you have to gain upward momentum while engaging in a air-spin (spin cycle physics in jumps are the same as arms are brought in tightly and that also determines how many spin revolutions a skater can accomplish. *Secret to great jumps is in the edge preparation before the leap.
What amazes me about spinning skaters is how they don't pass out from being spun so fast. I dunno if it's something one can actually train for as it's a physiological response.
I just watched that Action Lab video again and it was just as fascinating as the first time. I've actually got one of those powerball gyros somewhere. I'm gonna dig it out and have another play with it.
What surprised me about the video, is how the presenter didn't sync his hand with the motion of the gyro, which would have spun it up much faster as momentum is transferred.
Regarding that friction, when I spin my powerball, I can feel the resistance pushing against me as the power from my hand is converted to kinetic energy in the gyro. It's really something.