Can I use a different rubric from the one my students are using?
No. You cannot have two rubrics for one assignment.
What is the size limit for videos?
The individual file size limit for a video is 600mb. There are no limits on the number of file uploads you make, nor on your total storage.
How do I compress my video if it's too large to load into a Video Assignment?
For more information on video compression, please refer to the help article How do I compress a video file for faster upload?.