Apple changed some stuff on their Trailers Site and QT Browser stopped working.
With this QuickFix the Quicktime Browser will play Trailer again.
As of yet, this is unofficial, but i´m sure there will be a newer QTBrowser posted
on XBMCScripts soon.

Copy this over the old file in the root of your Scripts folder.
THX to bULLdOG64 from XBMC Forums for sorting that out ;-)