There are several popular news articles that refer to this video, who's notes point to the NASA news item NASA's Van Allen Probes Spot Man-Made Barrier Shrouding Earth which points to the interestingly named paper Anthropogenic Space Weather which reviews a wide range of phenomena over the last half-century but does mention VLF.
Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release experiments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.
Gombosi, T.I., Baker, D.N., Balogh, A. et al. Space Sci Rev (2017). doi:10.1007/s11214-017-0357-5
I don't understand how VLF transmissions from Earth have formed a "barrier" at all. Is this barrier protecting us from radiation in space, or does this only mean that certain particles are found to be at lower levels in certain areas of Earth's magnetosphere than otherwise expected? Is this something of significance to people or satellites, or just a deviation or fluctuation that is only being hyped as a barrier against radiation?
Are satellites in LEO receiving less radiation damage from the higher energy particles for example because of Human's constant high power VLF transmissions?
VLF transmissions from Earth are widespread, powerful and steady. According to Wikipedia most of the transmitted power is between 10 kHz and 100 kHz with wavelengths of kilometers to tens of kilometers. Usually frequencies above 30 kHz are considered LF rather than VLF. but there's nothing special about the 30 kHz dividing line. Because of the low frequencies and long wavelengths involved, some signal strength can penetrate the top layer of the otherwise electrically conductive Ocean and can be received by submarines. Other applications include time references.
above: "Long-wave transmitter of the Navy of the Bundeswehr, near Saterland-Ramsloh in the district of Cloppenburg (Lower Saxony); Located in the nature reserve" Roughly translated from German. (fyi it's the towers in the background, not the cows!) From here.
above: "Closeup of a few of the antenna towers of the U.S. Navy Cutler VLF transmitter facility at Cutler, Maine. It transmits operational orders one-way to submerged U.S. submarines worldwide at a frequency of 24 kHz with a power of 1.8 megawatts." From here.
above: "Radio towers of Varberg radio station at Grimeton (Sweden), which is today listed as a UNESCO World Heritage." From here.