Hi @AdultESLteacher ...
In the original course, are the videos included in the "Files" area of the course? How have you been adding these videos into your course? Are you using the upload media tool within the RCE (Rich Content Editor)? Do you, by chance, have access to Canvas Studio (a paid add-on product from Instructure)? Have you considered using YouTube to upload the videos and save course storage space? Just thinking of other ways you can cut down on the large IMSCC export file so that you're not having to deal with the issues you are experiencing when trying to import that file.
Looking forward to hearing back from you soon!