How is this webpage updating? Firebug shows no net activity?

http://uk.finance.yahoo.com/q?s=^FTSE&ql=0

I have 'net' enabled on firebug but I cannot see any activity whatsoever, yet the price is being up开发者_C百科dated?

Using streamapi. Open Net tab and look at http://streamerapi.finance.yahoo.com/streamer/1.0?s=^FTSE,USD=X&......

size of this file increases always

That's a nifty trick, I'd say! Look in the network tab at the very last entry (something like GET 1.0...). Then open the tab "Answer". You see, that this file never stops loading and spits out script tags.