Hi rgarafola,
welcome to the Apple (user-to-user) Community.
Re: "how to burn a DVD using the USB SuperDrive"
Wondering which computer / model (year) you are using,
and
which Operating System version is installed.
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Re: "How do I get the DVD on my computer as a video file"
In general, you can often double click on a disk icon as soon as it appears on the desktop, to open a menu that will allow you to choose to view the DVD's contents.
(NB: If an app should open and begin playing the video, you can (watch or) quit the app when you want, and the icon should be available on the desktop.)
Then from the folder that opens, it is generally just a matter of dragging the video file to the desktop, and waiting for computer to duplicate it. (You may see a progress bar)
Re: "then be able to eject it from the SuperDrive player"
Once the computer has completed copying the video-file, close the folder you opened. The DVD should eject as normal, as nothing on it is in use.
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You may want to create a "burn" folder to help burn the contents to a DVD disc:
NB: For accurate info:
Choose your OS version at the top of this article, if you are not using Ventura OS:
Create a burn folder on Mac to hold files to burn to a CD or DVD – Apple Support
All the best :-)