He was talking about dividing by NdotL.
BRDF explorer will multiply by NdotL outside of the BRDF, so if you've included NdotL inside your BRDF (as we usually do in games), then you need to divide by NdotL at the end to cancel it out.
Anyone have a database of more BRDF’s we can use with BRDF Explorer?
Also, Chris_F, be careful of this:
vec3 Rd = (Kd / PI) * Fd * OrenNayer;
vec3 Rd = (Kd / PI) * Fd * OrenNayar;