Hi, I have exactly the same problem. AE crashes when I try to select format option.
I have AE CC (2014) running on an iMac OS 10.9.4, 3.4 GHz Intel core i7 processor, 16 GB RAM. It happens even on the very simplest compositions with no plug-ins or even animation. It crashes when I attempt to change 'Lossless' to anything else.
Very annoying problem. I'm having to workaround by rendering Lossless and then going into AME.