The health hysteria over aspartame hasn't really been fully debunked, there are still countless conflicting studies about the effects of aspartame, one of the more recent ones finding the metabolic effects of artificial sweetener to be the same as an actual HFCS-sweetened soda.
Soda may or may not be bad for you, but it's certainly empty calories. He shows a picture of Diet Coke but mentions Vanilla Coke throughout. Your parent comment is on the mark.