As long as your Blackboard Administrator has installed the Echo360 building block and configured Blackboard to allow student video submissions from Echo360, all you have to do as an instructor is create a Blackboard Assignment the way you ordinarily do.
If your Blackboard Administrator has performed the proper steps to do so, once a student submits an Echo360 video as a response to a Blackboard Assignment, that video is locked down on the Echo360 side. The student cannot edit or delete the video once it is locked (an Echo360 administrator can delete the video if necessary).
The only thing you have to do is be sure to use the Assignments type of Assessment in Blackboard. When the student submission is tagged as an Assignment, it forces Echo360 to lock-down the content.
Your students, in responding, can select Write Submission to show the text box, then select Echo360 Video Library option from Mashups to submit a video from their Echo360 content library. Refer students to Submitting an Echo360 Video for your Blackboard Assignment for additional instructions as necessary.
When you review each student submission in the Grade Center, you will see the video they selected embedded in the review page. You can play the video from there and grade them right in the page.