Is it normal to jerk off with a buddy while watching porno together?

No.

That's a weird situation for any two friends to do that together.

Where do you come from? It's so normal as to be ordinary.

That doesn't sound like what two straight men would do.

That's incredibly gay

sure sure.
but don't be surprised if someone in the group decides to take it a little bit further each time you do it...

=)

yey lets all have a circle jerk.

Not something I could ever see myself being comfortable with, but if it doesn't cause problems with your relationship I don't see a problem.

I have masturbated alongside a male friend before to a porno. There was a mutual understanding that neither of us would look at each other though.

I'd say no... I'd consider that weird...