Yes, from the closer shots it did look like it was mostly men from their teens to their 40s (maybe this isn't the case). For those in the know, do families, young children, non-fanatics attend these events? Maybe they sit in different sections?
I don 't know about anyone else, but I go to games to WATCH the game, not to participate in coordinated fan choreography or something similar.
If you ever get the chance to attend a Kings game in G1C, I suspect you'll change your mind.
Can't speak for Nightfall, but when it comes to european football or in my case german football there are sections in the arena, that pretty much belong to the "hardcore" fans or like we call them here "Ultras". The Ultra culture is indeed a culture dominated by young males and plays a strong role in Germany as a self-proclaimed opposition to investors and companies, who have begun to play a bigger role over the last decades, because many clubs changed their legal form from what we call a "Verein", which is basically a fan owned legal form, to joint-stock companies.
So when attending a game a fan or customer pretty much has the opportunity to buy seats close to the Ultra sections in the arena, where tickets are relatively cheap and people are chanting and jumping (the actual Ultra area is often inaccessible for "normal" customers, because the seats are tied to season tickets and are all purchased by the members of one of the Ultra organisations). If the customer doesn't want to take part in activities of the Ultras, he can buy seats further away from the main Ultra section. Often those seats are a bit more pricely, but often they offer a much better view. That's where you will find most of the customers, who don't want their Kids to take part in the fan activities or worry about their safety or simply want to watch the game without getting distracted.
So basically it's entirely possible to just watch the game, while at the same time having a great atmosphere created by the "hardcore" fans of both clubs in their dedicated areas (there are guest fan areas in most arenas, often located at the opposite side of the arena, making a strict separation of the hardcore fans of both clubs possible). If the game is going great the atmosphere often will be contagious and the whole stadium will take part in the chants, but this isn't the norm.
But witnessing this fan culture is still truly remarkable, no matter if you take part or not. Watching the whole 10.000 fans of the Hamburger Nordkurve singing "Hamburg meine Perle", which is a song praising our city and home, will give me goosebumps and a feeling of homecoming every time. And while Hamburg is a great arena to be in, being in the arena in Dortmund and witnessing 25.000 fans (it's actually Europes largest standing stand) singing and jumping is an eye-catcher few will ever forget.
Like Nightfall already said - there are negatives, because like with every culture dominated by young males there is always the risk of violence, especially when drugs are involved. But usually things stay relatively civil.
And I personally can't think of a football game, without this kind of fan activities, even though as I got older, I usually buy seats in sections with a better view and focus more on the game than on chants.
