Flash photography at the Comcast center in Mansfield MA?

I'm going to the blink 182/ My Chemical Romance concert at the Comcast center on August 9th and from the reviews I've read they're extremely strict about a lot of things. But I've seen videos from concerts at the Comcast center on youtube, so do you have to sneak them? I plan on taking a couple videos as keepsakes and of course I want to take pictures with the friend I'm going with.

Also, the camera I do have is a Nikon D5000, which is pretty bulky and I've been told they probably won't let me in without a press pass

Your ticket will state that 'professional' cameras or recording equipment will not be allowed into the concert. Your camera is not a professional model, but try explaining that to a six foot meathead who is telling you to take it back to the car. They see a DSLR or a large camera, they deny entry with it, simple as that. Small compact cameras are (usually) permitted.

Why are you concerned about flash? Just how much use do you think your flash will be in a concert? The flash will be useful for a range of about 10-15 feet. It always makes me laugh when I see people using the flash on their cameras at sports events or concerts, somehow thinking that the tiny little flash on their camera is going to light up the whole stadium! It is pointless. Just up the ISO and use a wider aperture.

Leave your DSLR at home, take a small pocket compact to record some images or videos as a keepsake for the night out and just enjoy the night rather than see it all through a viewfinder.

Some concerts won't allow you in with anything bigger than a small compact P&S. Bringing it with you is probably not the best idea, concerts are crowded anyway and not ideal to get good pictures of. That is unless your in the photographer pit, which you need a press pass for.