The trick is the beneficiary rewards. I wrote a full article about it and even made a page to do it yourself if you want to share your articles rewards with someone else who participated: https://steemit.com/steemit/@heimindanger/split-the-rewards-of-your-posts-with-other-beneficiaries--only-on-steemwhalescom-
And it doesn't require more than the posting key, as you just add a list of beneficiaries along the post.
so dtube don't take those 25% automatically, it will take it just if we post on steemitwhales ?