This is an option on paid plans.
It allows the card creator to hide all videos from other contributors, meaning only the card creator and the final recipient will see the videos.
We encourage you to leave them visible as we find contributors want to be part of the tribe.
However, there are circumstances where you won't want contributors to see the other videos in the card, and that's what this feature enables you to do.
At 4 MINUTES & 8 SECONDS (4:08) in the following video you can see how to toggle this feature on / off.