In some cases, you don't want your learners to be able to see the activity description or uploaded resources of an activity until the activity has been unlocked (for example by completing a prerequisite or passing a deadline).
The default behaviour is that learners will be able to see the description and resources even if an activity is locked for them. To change this, navigate to the edit page for an activity and check the "Hide description & attachments if the activity is locked or overdue".
For a video activity, this setting will also hide the video for learners when the activity is locked.
How it looks for learners
If a learner tries to access the activity while it is locked or overdue, they will see a message telling them that the content is hidden until the activity has been unlocked.