The FAA tends to be more reactionary versus proactive, and they have been for years. This means that it is very unlikely they will be showing up unless there is an incident or accident, and if violations of the aviation regulations are found to have occurred, they will likely take action. This also means that they do not bother watching YouTube and looking for violations. There were stories during the peak of Covid suggesting that agents were working from home looking for UAV violations on YouTube, but if even true, I know of no official investigations that occurred.
Regardless, many claim to use visual observers as mentioned above by
@Tony McDrone, and nowadays, it would be very easy to say that the video was not real and a product of creative editing in order to increase subscriber count...
I will admit to flying a bit over BVLOS, but I only do so over large areas of water where a worst case, inflight failure would simply result in the copter taking a swim, with no threat to persons or objects. I would never do so over land, and although I may not be able to see the copter, I can clearly see the airspace that it is in, and in the unlikely event that a manned aircraft shows up at 150 or so feet, I would be able to both hear and see it prior to there being an issue.