I would agree that you should always try to assume the best (and I didn't actually suggest he doesn't understand), but he certainly explains it clumsily, and his explanation does not illustrate the difference between a median and a mean, or when one would be more meaningful than the other.

I don't think it's the best explanation, but I do think he understands that mean as a measure of central tendency is not that useful when distributions are skewed or multimodal (the squiggly line gesture).

Yes but:

1. If data is multimodal (wiggly line), the median isn’t a great measure of central tendency either.

2. Perfectly normally distributed data will have the same mean and median.

I agree people have jumped on this as evidence the guy doesn’t understand when he probably does, but what he says is a long way from the truth.