There is a FAQ in the Licence.
Please read it. I wrote it to clear up all those questions.
The first point says:
1.3) FAQ:
Q: May I use and distribute screenshots/videos on social media & game stores if I buy these assets?
A: As soon as there are screenshots for a project publicly shown, the license for the assetpack is automatically tied to the project shown. This acknowledged, screenshots and videos may be shared.
(3.1A, 3.1B)