The default setting for all folders are set to "immediate"(all students will be able to view the content immediately once it is uploaded).
Turn off sharing (whole folder)
- Click on folder setting
- Go to Settings>Availability, change it to "never"
- The video will now be shown as "Not available to viewers"
Turn on Sharing (individual video)
- Click on Settings under each video
- Under Overview>Availability, change the setting to "now"
- The video now will be available for all audience