The footage was shot with the Log-C profile. Preserves the dynamic range and is very pliable for grading. I use Nick Shaw's Log-C-to-709 LUT filters and they work great for editing. Then for the final, strip them out and grade in Color using ARRI's LUT for Color. Review these blog posts I've done that cover this and it should become clearer:
http://digitalfilms.wordpress.com/category/arri-alexa/
- Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com