I'm not saying he shouldn't outsource his videos. What I'm saying is that this looks more like a professionally made commercial (advertising his personal brand). I'm pretty sure it cost O(hours) of his time (consider even getting to the set - you can see this is a professional set, so probably in some studio; I also doubt this was done in one take given how there are other actors around including the skating Santa Clauses). All in all, it really feels artificial and dishonest. What kind of person would even come up with idea of creating such a video in the first place?
There are somewhat diminishing returns spending money on philanthropic causes: if he were to spend 30 rather than 3 billion the result wouldn't be ten times better. I'm happy he's trying to make the world a better place while still keeping an eye on the money being used efficiently.
Why does the 100k matter if the 3 billion don't?
My 2 mins of googling came up with more like 3.6B$ on malaria, but even 2B$ is a shit-ton of money. I certainly haven't donated 2% of my net value to malaria (and it's only on the order of 1/10000 of his!).
Malaria rates are down around 30% since 2010, thanks in part to Gates. He's likely saved thousands to hundreds of thousands of lives.
Malaria is just one part of his philanthropy. I'd love to see the numbers for Jeff Bezos or Elon Musk. It would be great to all billionaires follow suit with this kind of "easy decision".