It's been a while since I saw the videos. Probably the biggest issue I could see leftists having with it is that first-year economics generally emphasizes marginal utility as an explanation of value, whereas Karl Marx (and, indeed, almost every economist in Karl Marx's time) subscribed to the labour theory of value. But a lot of the concepts are still useful independently of that, and it's a good idea to understand marginal utility if you want to argue against it anyway.

He doesn't spend the whole time going "AND THIS IS WHY COMMUNISM NO FOOD ARGLEBARGLE!" if that's what you're worried about. It's mostly just neutral explanations (insofar as it's possible for such a course to be "neutral" when teaching neoclassical economics), the same way he would explain a concept in math or science.

EDIT: See TossedAccount's and dan26dlp's replies to my comment for other things to keep in mind.