Firm Up Your Wares - With Canon
The upgrade will enable the camera to use their HDMI output to send uncompressed video data to an external recorder. This means minimal degradation during video editing. Additionally, the video you are recording can simultaneously be displayed on an external monitor while you are capturing it.
The photographers who want to use long lenses with teleconverters are now assisted by a boost in the AF capability. You could couple a 600mm lens with teleconverter to yield 1200mm focal length and work down as dim as f:8. You also get a coincident increase in activity and focussing ability if you use 1.4x converters or 400mm or 100-400mm lenses.
Please search the official Canon website for directions to the free download area.