Log into Blackboard Learn as Administrator

Access a Test in Original course

Enroll 2 or 3 Students

Create a Discussion in the course and make it available

Add a starter thread as the Instructor and a video attachment to it

Login as the test students, and start replying to that starter post (make sure you include heavy attachments, like videos, audios or images)

Then, back as Admin, go to Courses> look for the course ID you have tested with

Click the chevron right next to the ID and click "Export/Archive"

Click Export Package

Select the options:
Copy links and include copies of the files in the course default directory
Copy links and include copies of the files outside of the course default directory

Under Package Size, click on Calculate Size, check the expected size

Under Select Course Materials you can "Select all" or select specific items as long as "Discussion Board" is selected

Submit

Wait for the package to appear under Packages created manually

Download it