Even if everything they say is true, that wouldn't prove a video is fake, at best it proves a video is real. If people will accept "our high-profile defendant in the segregated housing unit of a maximum security prison hung himself with a makeshift noose fashioned from blankets off a bedpost that isn't even as tall as he is while the guards were playing 3d space cadet pinball and the camera was broken and his cellmate was in solitairy", surely they will accept "our maintenance guy used regular lightbulbs from home depot instead of the super secure digital signature bulbs".

Or maybe "we installed the right bulbs but then we set the cameras to record in 240p MPEG with 1/5 keyframe per second because nobody in the office understands how digital video works".

Anyways I'm of the opinion that the ultimate end-state of deep fakes will be some sort of hybrid system where the AI creates 3d models and animates a scene for a traditional raytracing engine. It lets the AI do what its best at (faces, voices, movement) and eliminates most of the random inconsistencies. If that happens then faking these light patterns won't be difficult at all.