Individuals have been doing this exact thing without AI for years, only better, with actual comedic timing, by just playing both parts. Sometimes they don’t even change clothes and it’s perfectly understandable. It’s a whole meme at this point that a towel on the head of a man signifies a female character, for example. You can find plenty of this on tiktok or instagram.

At least for my enjoyment of the Gossip Goblin videos, the world and aesthetics are pretty critical to it. I wouldn't find it at all compelling if it was just someone in their kitchen playing it themselves. I do like those videos with people playing both parts in other contexts (comedy particularly), but for other types of work, the AI generated videos are doing something that can't really be done yourself unless you become a Blender virtuoso.