Hello & welcome !
Could you help me change the system in one of them?
This is not possible with CHDK - CHDK only supports Powershot cameras, no video cameras.
On most Powershot cameras you can change the video system (PAL / NTSC) from the menu / original firmware; if this is not possible on your HF100, IMO the only way
would be a firmware update / change - but most probably Canon will never publish such an update...