Why is potentially the worlds finest discovery of the 21st century being communicated using the worst software to be cobbled together in the 20th? (Aka Flash)
It works. Flash Player is the only browser plugin yet that can do an actual streaming (not progressive download) using either Adobe's own Media Server or other similar Open Source at the back-end. If need be, that is the best form of protection against content theft so far.
It is not that difficult to setup the whole streaming with lots of free and open source solutions available today. It's just a good means to a useful end.
EDITS:
Just as I suspected, it's using a Media Server Streaming Server.
"rtmp://cern.fc.llnwd.net/cern/"
It is also automatically streaming corresponding quality depending on the user's bandwidth.
Latest application of the uncertainty principle - you can have 21st century discoveries or 21st century technology, but you can't have both simultaneously.