Ehhh gotta disagree, if he's doing slow cardio he should be fine for burning fat. If he's not exerting enough effort to burn carbs the body will switch to burning fat instead since it's a more efficient source of fuel. I haven't seen his videos so dunno if that's what he's doing.
that seems to make since when you phrase it that way
BUT
insulin has a big effect on matebolism - fat metabolism specific.
carbs = insulin = no fat burn
i might be wrong though.. ive heard after 20 mins you burn fat...which never made any sense to me... maybe that is a rule that applies to doing cardio after eating carbs?