Students can only submit Kaltura video assignments using the Insert Stuff button, which is available on the textbox.
That is why it’s so crucial that you select the right submission options for a Kaltura video assignment. If you want students to record a presentation and submit that through an assignment (assignment tool), you need to select the “Text Submission” for the submission type. That way, students can access the Insert Stuff button to submit their video for grading.
If your students don't use Kaltura to record a video, they can still use the Insert Stuff tool to upload a video from their device.