Unlike Moodle Assignment, Video Assignment does not cater for students submitting in groups. It can only be set up as an individual assignment.
If you would like students to submit group video assignment, the workaround is to use Moodle Assignment instead. Under Submission type on the Settings page, disable File submission, select Online text.
Students can then embed MediaSpace video by selecting the Embed Kaltura Media button on the online text editor.
Please note that video submissions are locked on the assignment deadline. Any edits that students
make to their videos will not be reflected in their submission, unless they resubmit to the Moodle assignment point.