It's a rather interesting development - sort of crowd sourced firmware for the Canon cameras - specifically turing them into 'proper' movie cameras with manual instead of AGC audio, selectable crop marks on the LCD for 16:9, 4:3 etc etc - Live audio metering on the LCD - more control of aperture and focus in real time.
Being crowd sourced, you can also create or pay to have created your own upgrades to the firmware with new features.
Has been super solid with no reported issues with supported Canon cameras.
Understand that the new firmware features bleed into stills as well, but have not looked into this area