Kaltura - How to Add a Co-Publisher or Co-Editor
The owner of a Kaltura video can give other users permissions to edit their videos and to publish them into Canvas courses.
Once you've given another user Co-Publishing rights to a video, they can insert it in Canvas (or elsewhere) by following the steps in: Kaltura - Inserting Videos in Canvas.
One you've given another user Co-Editor rights to a video, they can trim, clip, chop, or add quizzes to it by following the steps in: Kaltura Video Editing Tools - User Guide. They can also add or edit captions by following the steps in: Kaltura (Captioning) - Adding and Editing Captions.