There's complete demonetization where videos have no ads altogether (e.g., videos from BBC if you're in UK).
There's partial stuff like Content ID matches. If you post my song, YT still shows ads, but you get no money. I now get your ad money (and YT its cut).
Not sure what they meant in case of Russell Brand, but I bet they will show ads for advertisers who don't opt out and pocket the profit.
I have noticed quite edgy videos that were ad-free before now heavily feature ads, so not sure about that. Many advertisers are not even based in the US, UK or any western country.
Not showing ads is the same as just burning money for Google.
I would not be surprised if there is some P(controversy | viewing user, time elapsed since original flagging) metric, and when it goes below a threshold, certain non-prestige or international ads can be shown - ads not likely to cause any problems.
There's partial stuff like Content ID matches. If you post my song, YT still shows ads, but you get no money. I now get your ad money (and YT its cut).
Not sure what they meant in case of Russell Brand, but I bet they will show ads for advertisers who don't opt out and pocket the profit.