Why are you videoing it on your mobile phone? You utter, utter, utter twats.
The sound will be rubbish - the picture is pointless as it is just a blur of flashing lights - and it's only 250 by 250 pixels. It is as pointless as you are you depressingly obsessive nob-ends. Standing throughout the gig with your arm aloft - looking at your phone's screen, not the stage, and blocking other people's view whilst missing out on the reason for being there - to jump around, mosh, sing, clap, dance and generally enjoy the moment and be part of it.
You are trying to capture it for posterity but don't actually enjoy the spectacle whilst you are there. What a lovely memento of the night you stood there like a lemon holding a phone in the air. Oooh, put it on facebook!
If you ever ended up in a situation where you got a naked girl in your bed (unlikely, I know) would you just video her on your phone rather than actually having sex? Result - you're still a virgin but at least you can look at a tiny image of her naked body any time you want and send it to your friends. Sorry - "friend".
You sad no-lifers really should stay at home and watch some grainy footage on Youtube because more and more of us real fans are getting sick and tired of you bumbling around trying to record everything and the next time you're in the pit it won't just be your Nokia that gets broken.