That's the way I understood the video.
Let's say the bridge is flat and takes a 200 x 55 shock. If you replace the bridge with one that has a 5mm bend down in it then you can fit a 205 x 60mm shock increasing your travel but the bike hasn't changed in the static position, or a 195 x 50 to reduce the travel if the bridge has a 5mm bend up.
Of course, I don't have the bike and I may have misunderstood the video but that is the way I understand it.