where you can sell videos? would be a good idea to add the video section in the marketplace. or can I insert in the ebook?
I would go with the Services forum with-in the Buy, Sell, and Trade category. https://forums.digitalpoint.com/forums/services.60/
Probably first you need to become a established member by getting 3 likes or become a premium member , then you will be able to post in BUY / SELL forum. There you can create a thread with a link to buy your videos & prefer to accept only payments through DP's INSTA pay or whatsoever , so that you will be protected (if I'm not wrong) & you can also leave a feedback on the transaction to authenticate it.