He never says this. He says the measurements fluctuate, which means the speed of light itself may (or may not) fluctuate. But we will never know because it's been defined as a constant.
Ok. In related news, I tried to measure the length of a day the other day (just to make sure we're not being had) and it was 29 hours long! My watch was broken, but still - 29 hours! Could it be that some days are 29 hours long? We'll never know, I guess. But I personally have my doubts, and plan to share them in a future TEDx talk.
