beyond the fact that at least 90% of the videos are make-ups and hoaxes of borred people.
The sound phenomena are very real.
In Europe there are many people suffering from this type of sounds.
A short intro in this (still talking about europe) showed me, that all these frequencies are heard in areas where military bases and/or airports around.
I once realized it myself, and if must have been something far more than just a sound, for I thought I'd be in a sauna.
After years I discovered, that around airports and military base are lots of towers whhich radiate in microwave frequencies. This is still not explanation for the sound, but this is probably a consequence of it.
There are even recordings of the humming tones in Berlin, and the most famous are those of Taos in NM.
blessings