I agree with it being an animation with no actual person in the video. Those are simply much more interesting to most of the internet, I think, whereas showing an actual person with a chalkboard is probably going to look comparatively amateur and kinda shoddy. Think slightly grainy, poor acoustics (almost definitely) that makes it seem filmed by some student for a school project...which is really just more a case of I doubt Rooster has professional recording equipment.
Whereas with a smaller animation and simply a voice-over, all we really need is an animator and a good microphone (which Crudblud might have, I don't know?).
Another important thing, I think, that a lot of people overlook, is that we should make sure to check the voice-over first. Moreso if Thork does it—no offense, it's just that Crudblud seems more like he'd be more inclined towards professional-sounding readings. I'd done acting and voice-over stuff in school for years, so I get overly critical about this stuff and get really upset with amateur readings where it's clearly from a script.