Should I charge a YouTuber for sharing my successful short?

It might be helpful to negotiate a fee that reflects the performance of your short. Given its success, this could be a great opportunity for you to establish a fair rate that acknowledges the work you put in. Even if the YouTuber is looking for free content, you have every right to ask for compensation for something that has already generated significant interest.

I think you should absolutely consider charging them. Your short has proven its value with its massive view count and continued engagement. If they are interested in sharing it, they recognize its potential value, and you should too. Charging a fee can also set a precedent for how your content is valued moving forward.