What is the Conservation of Angular Momentum?

Very nice presentation. You could perhaps mention that kinetic energy is not necessarily conserved within the system when the person does work on the spinning object he's holding or her limbs, respectively. But that would perhaps complicate things a bit too much and subtract from the crystal-clearness of the video's point. A a suggestion you could do a complementary :)

your presentation is amazing. thanks.

Is this where the phrase "the tables have turned" comes from, in the context of a situation where 1 person does something to another person, then the the same thing happenes, but it swithes between the 2 people?

awesome!!!

Torque sounds cooler. ;)

By the way, I do not like the first sentence : "Nature conserves spinning" which has no sense to me. There are basic laws in Physics and this is not one and this is why I prefer to you the Coriolis effect in that frame : because Coriolis effect is the direct consequence of Newton's laws. Nature conserve... Newton's laws... ;)

Step 2 / the skater takes hands back to the body. The linear speed
of hands tend to be slowed down more and more when the skater take the hands back to the body BECAUSE of the efforts of the skater (otherwise the right arm would to go toward the front of him and so forth and the left arm would tend to go toward the skater's back / if no efforts are applied)

If you imagine that the angular speed of the vertical axle is fixed (e.g. by a "stubborn" motor), when diminishing the radius, the weights and cable would wind up around the axle !

Was I clear ? What do you think of the idea please ?
This explanation has the advantage to not use the term "Angular momentum" and replace it with Coriolis. Where is the point ? I feel that Coriolis is easy to explain without equations or theories of anykind.

Step 3/ Application of Third Newton law : there must be a reaction to these efforts and this is the acceleration in rotation speed.

PS : I talked about "efforts" of the skater but this would work anyway with cables and weights (thanks to cable tension).

OK, this is the "classical" way of explaining things.

Let's take the skater : I tend to like another explanation relying on the Coriolis effect and I would like to have your opinion on it. To simplify, let's assume that hands are "weights" and arms have no mass.

Step 1 / the skater has hands far from her body and hands are going fast in linear speed (at instant "t").

great vid ^_^