made a tutorial about installing this to have clean hdmi out on the eos m3 
maybe it might help someone
Nice effort. There are two things not quite right though.
First of all CHDK is not a firmware mod. No changes are made to the firmware on your camera. When you remove the CHDK enabled SD card, you are back to your original camera setup. That's actually a nice feature - no risk of bricking the camera like you get with firmware mods.
*Which brings us to the other issue.
All those files you dragged onto the SD card early in the video? They are specific to both the camera and firmware version. The files that work on one model's firmware version won't work on the same model camera with different firmware versions. And they certainly won't work on other models. So somewhere in your description you will probably need to explain how to figure out what firmware is in a camera and which files to use?
*EDIT: the point about CHDK not modifying your firmware is not just sematics. You will need to install it on every SD card that you want to use with disabled overlays. CHDK "goes away" every time you turn your camera off and has to be reloaded when you start again. Fortunately, the steps you followed cause an automatic reload
