That sounded suspicious to me, so I pulled up the HBO Max promo clip shared months ago. The first piece of footage used comes from "Devil May Hare", which is on Boomerang. There's also a classic Scooby-Doo clip near the end, which is also prominently featured on the app.
Would be weird to have footage like this featured if they won't be on here.
Would be weird to have footage like this featured if they won't be on here.