Yes, freedom of speech is part of what we defend, fight and die for. I will admit to being unsure of where the line between legal speech, and speech designed to incite violence is... because SCOTUS has clearly opined that not all speech is free speech.
When it comes to speech which is designed to incite violence, as this film clearly was, then I don't believe it's covered by constitutional freedoms. Since when are Americans allowed freedom of speech which is designed to get other people, including other Americans, killed? Someone said we should stop the "barbarians". Okay. How? How many countries do we bomb into extinction before all the "barbarians" are destroyed? We're clearly not very good at merely conquering countries, and schooling them to our superior ways. How many people are we willing to kill? How many of our own people are we willing to kill?
This is not a black-and-white, beat-our-chests-for-the-constitution issue. It is a global issue.
In a perfect world, the US would gather intelligence leading to the actual perpetrators of the destruction/murders at the Libyan consulant, shove a couple of drone strikes up their ass and show the rest of the rabble what they can expect if they **** with us. It's not a perfect world, though. So... how many people should we kill to protect our constitutional freedom to insult other religions. I'm just asking.