The video shows a modern redo of an experiment first done in 1887 by Albert Michelson and Edward Morley.
Physics theories of the late 19th century postulated that, just as water waves must have a medium to move across (water), and audible sound waves require a medium to move through (such as air or water), so also light waves require a medium, the "luminiferous aether". Because light can travel through a vacuum, it was assumed that the vacuum must contain the medium of light. Because the speed of light is so great, designing an experiment to detect the presence and properties of this aether took considerable ingenuity.The experiment showed no aether. When done on a flat table "parallel" (tangent actually) to the surface of the earth.
Earth travels a tremendous distance in its orbit around the sun, at a speed of around 30 km/s or over 108,000 km per hour. The sun itself is travelling about the Galactic Center at even greater speeds, and there are other motions at higher levels of the structure of the universe. Since the Earth is in motion, it was expected that the flow of aether across the Earth should produce a detectable "aether wind". Although it would be possible, in theory, for the Earth's motion to match that of the aether at one moment in time, it was not possible for the Earth to remain at rest with respect to the aether at all times, because of the variation in both the direction and the speed of the motion.
The experiment in the video shows "something" if the rotation is done with the device perpendicular to the earth. Of course one thing that could confound the experiment is a distortion of the "table" by gravity. Or it may be that the speed of the light "waves" is affected by gravity. More complex experiments should be able to sort that out. If the effect demonstrated is not just experimental error we are definitely going to learn something important. A shift of 11 fringes with a 532nm wavelength (if I understand his counting method correctly) is an effective differential shift in length of about 5.8 micro meters.
For those of you who want to dig deeper, have a look at this interesting discussion of the original Michelson–Morley experiment.
Let me add that the Mossbauer effect experiment done vertically (it has been done) tends to argue against a change in velocity (actually frequency since the speed of light is constant) outside the expected range (due to gravitational effects on light).
Most interesting to me is that interested amateurs can now do experiments on the cheap that would have once required a rather sophisticated laboratory. Who knows? Some one may learn something useful.