It is just mass hysteria and yes thousands of people can make false claims due to this. In medieval Europe whole villages used to claim that they actually saw the witch perfom that un-natural act. BTW its odd that they never had UFO claims those days. These seem to be a 20th century, American phenomenon.
I've already shown UFO sightings are not in any way limited to America. There are UFO reports all around the world. The video talks about a Japan Airlines Pilot on a 747 who reported they were being followed by a massive, fast moving object. Radar confirmed this object was there. The co-pilot confirmed this object was there. The radar track and the pilot confirm this object was moving at seemingly impossible speeds and moving changes in direction no known aircraft could duplicate. That pilot was grounded by the airline after making this claim even though there was radar evidence and he had an otherwise normal record.
There have been countless sightings in Mexico, South America, Europe, and Russia. Most sightings do not produce great evidence though so they were ignored for this particular documentary (aside from the Belgium and UK incidents) - but no one can say UFO sightings are only made in the USA.
And finally, perhaps the people of medieval times who had never seen an aircraft fly, never seen even an internal combustion engine, - people who did not have a common point of reference that we do today didn't call them "UFOs" but instead called them Angels, Demons, or other super-natural entities that there are no shortage of reports of throughout human history.