I went into YouTube Studio and it says the issue is the in-game music. Because of copyright, my video will be blocked in some territories and can't be monetized. Joke's on them - I don't monetize anything. I don't want to harass viewers with ads. I'm just happy if people view it.
I added another clip from a Twitch stream. To my surprise, YouTube says it's partially blocked. I'm not exactly sure what the issue is.
I'm back, this time from Monte Carlo.