If you are in a public place at a public event, it is almost inevitable that someone will get out a camera or camcorder. If it is of sufficient interest for a TV camera to go along, it is unlikely that they would go round Xhundred people and ask them all for permission to be shown on TV: so why should someone with their own camera have to ask every single individual by putting what is widely acknowledged to be a fun event for others to enjoy on Youtube (picture and sound quality good by the way!
It is a different kettle of fish entirely if at a concert given by paid (or even umnpaid) performers: then if it was not forbidden to film, I would routinely ask the performer for permission to broadast the footage: would do it as an "unlisted video" first so that the perfomer could view it privately before giving permission for it to be made public, or I would just make them up their own DVD of the event.
And I agree entirely about the gross irritation caused by photographers, both unofficial and official crawling about all over the place, sticking their long lenses right into your field of view, clicking and flashing, as well as now, it seems, shedding either green or red/orange light on their intended subject as they set the focus. I give great credit to the performers at one event I was at in June, for managing to keep going undeterred against this battery of photographic assaults. (How necessary is flash anyway: it adds nothing from a distance, and can be turned off in most cameras). A word with the organisers did result in a marked reduction on the second day of the event.
But if they need a still photo, as someone else has said, why can't this be taken before or after the concert, or during sound checks?
At another event, the official photographer thought she was being so unobtrusive by crawling around below a rather high stage, but she was painfully visible and very distracting (large expanse of bum cleavage included!)to anyone sitting in the first few rows of the auditorium.