Just experiments that make energy.

What is being ignored in the videos is the conservation of angular momentum.  I studied that many years ago in college physics.  What I am talking about is the same principle used by figure skaters to increase their spin rate to a high speed and then stop spinning very quickly.  A large slow spinning object will increase greatly in rpm if the mass can be brought closer to the center of rotation.

A simple and fun experiment will demonstrate this.  Find a chair like an office chair that has good bearings so that it will spin easily.  Sit in the chair with your arms and legs extended out as far as you can get them.  Now have someone give you a good spin.  While spinning, pull your arms and legs in as close as you can to your body.  You will feel the chair speed up in rotation.  When you extend your arms and legs again you will feel the chair slow back down.  If the bearings are really good in the chair you should be able to again retract your arms and legs and again feel the chair speed back up.  You can repeat these motions until the drag of the bearings and wind resistance slows you down.

There is no extra energy gained but this is an interesting example of the conservation of angular momentum.  I don't remember the formula for calculating it but I am pretty sure there was one we used when doing the experiments.

Carroll

The formula for angular momentum (L) can be found in Wikipedia; L = r mv where r is the radius of rotation (sometimes called the moment arm) and mv is of course Linear momentum.

The formula in Wikipedia is just to the left of the vector diagram window.

This formula can be checked by applying it to the appropriate place for which it was invented: planets comets and other satellites. You take the product of the long radius and the slow speed (mv) of Haley's comet at apogee; and compare it to the product of the  smaller radius and fast speed of the comet at perigee; and those numbers will be the same. This is conservation of angular momentum.

The speed change of the comet  is caused by gravity. But gravity does not cause this kind of change in the laboratory.  Gravity does not increase the speed of the barbells as the student; spinning on the chair; pulls them in. Then why does angular momentum conservation work in the laboratory? Well it doesn't. There will be an increase in rotational speed because the radius of rotation has decrease but the new speed will not fit Kepler's formula for satellites.

You will never see; in common use; an angular momentum conservation experiment conducted where the experimenter carefully measures the changing radii of the rotating mass. An experiment that is done well will be ignored by your professors. And the results scorned by the same professors.

One good example of this is Galileo's pendulum conducted over 300 years ago. Galileo used pins to interrupt the string of a simple pendulum in the down swing position; and the radius of rotation changes. The mv of the long and short pendulum sides is the same at the down swing so the changed radius changes the angular momentum. Thus angular momentum is not conserved.

Let's look at a despin experiment where the cylinder is stopped. In this experiment the attach spheres are 500 grams each and the cylinder; that is at rotational rest; has a mass of 10 kilograms. The radius of rotation of the spheres are 24 times that of the cylinder (cylinder r = 1.75 inches, 4.445 cm). The spheres are moving 1 m/sec; at a radius of 24 times that of the cylinder (42 inches, 106.68 cm); when the cylinder is stopped.

The original angular momentum is therefore 1.0668. If the spheres were to wind around the cylinder and draw into the same radius then you would have 11 kilograms all moving at v meters per second: so that 11kg * v m/sec * .04445 m = 1.0668.  That would leave us with a linear velocity of 2.1818 m/sec. for the entire 11 kilogram system.  So angular momentum conservation would require that 1 unit of linear momentum would produce 24 units of linear momentum. This production of 24 units of linear momentum from 1 is a clear impossibility. In any closed system (no application of outside force) the linear momentum always remains the same.  Angular momentum conservation does not work in the lab. 
 
Another proof would be to place an immovable post in the middle of a frictionless plane; have a puck on the end of a string wind or unwind from the post. The radius of the rotating puck would be constantly changing but the linear Newtonian velocity of the puck would remain constant. As the puck rotates the radius would shorted (or length if unwinding) for each orbit of the post. An infinite number of radii would multiple the same linear momentum (L = r mv); for an infinite number of angular momentum.

If the student on the chair, with barbells, can reduce the radius of the mass to one half then the rate of rotation doubles. This is the increased motion you see; but the linear momentum has remained the same.