[Sandbird]

I am using xbmc-20140727-d365123-master-i386.dmg (latest nightly build) on a Mavericks 1.9.4 and i have a weird problem.
All online videos over 480p are grey. 320p works fine but everything higher is as if the codec is busted.
This is how it looks:


Any idea why ?

My hardware:
Core2Quad q660 2.4ghz
ATI Radeon 5770 1gb
Kingston 4gb DDR2
OS: Mavericks 1.9.4