whats up everyone,

was just trying to figure out the rhythm part for the song 'say' by john mayer (as he plays it in his videos, though there are many tabs online, none of them are true to how he plays it), looks like an open tuning with him playing a C major and G major finger positioning around the neck but can't fully figure out whats going on

here's a few videos to help: http://www.youtube.com/watch?v=XWrIcISW0A8
http://www.youtube.com/watch?v=M7YAR9a0oYs (both start at 1:00)
and the official video which has some clips of him playing: http://www.youtube.com/watch?v=YZ0z86LmXBM&feature=fvw