I have been shooting some video lately with the EOS-M and notice the video files are much larger than comparable files from my Oly EM5 or Panny GH1.
EOS M doesn't compress audio into a lossy format. It records audio in Linear PCM. This could affect file sizes a fair bit.
|Black on White by RaVN11|
|Hummingbird and Bee by dibilio57|
from A Big Year - birds
|xheneta iseni _for DPReview by Mike Slade|
from - My Fair Lady - (Portraits in Full Colours Only + A Border)