Well, I checked the video link – he is talking how to use the cam for wedding AND with camera off flash – hence using (M)anual mode, but no word about camera metering.
To change from Matrix metering to Center weigthed (custom menu → b5 preset) or Spot metering, just hold down the equivalent Metering button (top right of your cam, next to the display) and toggle / skip through them with a right / left flick of the custom dial (top right on the back).
I suggest to try out, what @Joanna explained in full length and compare to what you are used too.
It’s important to get a feeling for what you (your cam) can do.
[Personally, I use the center weigthed metering (12mm circle) and adjust exposure with the aforesaid custom button, but different to the fellow’s (tiring) video explanations “d8 → EASY ISO OFF” and some more …]
just saw, you got it twice – so …