Stripe Connect and Braintree are set up for marketplace scenarios but you'd need a company. Possible to hack together something with the PayPal API too, simply paying out to an email address.
You absolutely need a company, and a chat with an accountant before you start singing contracts with and paying partners who create content for you.
If you just wing it, there's a good chance that you will end up owing the government employment taxes.
Is that something you can do with just a simple individual account? Or is this something you need to upgrade your account for? If it involves upgrades, does it have monthly fees? Does it require a business account?
Found a couple of overviews, but I don't see all of the above questions readily answered:
https://www.paypal.com/cgi-bin/webscr?cmd=_batch-payment-ove...
The links I posted suggest the sender pays a fee upon use of MassPay, otherwise, no. There is no extra fee. Though I don't have a business account, so I don't really know what that entails.