I only go to metal and punk gigs. No one talks because the music is so loud it would be hopeless. At the front, where I like to spend the evening it would be near impossible to hold up your phone to video it as 50 people slam in to you as they mosh. As for fans getting lost in the music, that's up to the band to take us there, grab us by the throat and keep going until the end.
The only rules in the pit at metal shows are never intentionally hurt anyone and if someone falls down, pick them up (or if they need help then help them)