You will need the assistance of a D2L admin to complete this process.
If the E-Reserves video has been added to Panopto, then you can directly embed the video in a D2L course. You may need to search all Panopto content in order to locate the video, and you will need to ensure the permissions on the video are set in such a way that the destination D2L course students will have access.
You may also search within the Ares streaming Panopto folder within the Library folder.