What is today's 'crowded theater'?

Justice Breyer appeared on Good Morning America this morning to plug his new book, Making Our Democracy Work.  About 2/3 into the video linked below (trouble with the embed), George Stephanopolous asked whether the backlash from the proposed Koran burning earlier this week poses a problem for the First Amendment.  Breyer dodged a bit, but does tip his hat to Holmes' notion that the constitution doesn't guarantee a right to shout fire in a crowded theater, "because people will be trampled to death." 

True enough.  

But what does that mean when the shout is heard around the world, because it's posted on the internet?

GMA video link here.

-Kathleen Bergin