No, its a bit more involved than that.
To get into an event for free, you are expected to at least build a bonfire and watch it for awhile. Some of these events cost upward of (including the most recent one) $100 bucks to get in, and some nearing $1000 for the week-long event.
At the larger venues, you are expected to work a number of three-five hour shifts, usually broken up into:
Bust: Cutting down trees, chopping them into logs, and hauling them to the site.
Build: Constructing the bonfire itself, making sure its stable, will look good while burning, and safe (most bonfires of the size and type I build have people within a few feet of them, so they are designed to cause people to "bounce" if they stumble drunkenly near them.)
Tend: The real meat of it. The pile is now on fire, and the party is in full swing. This is the shortest shift, usually only lasting three hours due to its intensity. You've got a 10-30 foot pile of flaming timber behind you, drums, bellydancers, fire spinners, drunks, druggies, naked, nubile hippy chicks grinding on you, etc that you have to more or less either protect or ignore so they don't get eaten alive by the bonfire. That's first shift. ( dusk till 1 AM)
Second shift, you now have most of the people drunk, off duty firetenders (who are the craziest, most dangerous fucks at any gathering) and usually weather to deal with. Its getting cold, and people start to crowd the fire, forcing the dancers/ partiers closer to the flames, and therefore you, as the firetender, closer to the flames to keep everyone safe.
Thiird shift. Most people are asleep/ passed out. Pretty easy shift, but the most dangerous cause at dawn, the firetenders go off duty and start partying.
I've seen firetenders:
Walk coals
drop 60 foot trees while drunk as hell
swing like Tarzan over the flaming pit from a rope tied to the center of huge geodesic dome
etc.
Basically, we go absolutely crazy when we go off duty. At the most recent festival, we broke in the food vendors kitchen ans started cooking, taking money, setting our own prices, etc. for example.