Dear respected Carl Mann,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description,
Open your web browser and log in to your SharePoint site using your university or organization credentials via access www.Office.com and click on 9 dots and click on SharePoint.

Go to the document library where you want to upload the video>click on the “+New” button (toolbar at the top) and select “Files.” Navigate to your video file on your computer and select it to upload.

After uploading, click on the video file to select it. Look for the "Share" option usually found in the toolbar and type the email address of your professor to share.

Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.
I'm sorry and I apologize for that.
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad