If you only have a few students with this issue it is most likely an issue with the device (or browser) that they are using to access the videos. The most common cause of this issue is related to the blocking of third-party cookies and/or the use of an incognito/private browser.
In order to successfully authenticate and pass permissions Panopto specifically does need the browser being used to accept cookies. Please see the following page: https://support.panopto.com/s/article/panoptos-use-cookies
To resolve the issue it is recommended that the Safari incognito/private browser option is never used. We see issues with this browser across all devices. Instead, D2L should be accessed using either Chrome or Firefox. If there are still issues we recommend allowing https://d2l.depaul.edu to set cookies and/or accessing D2L not using an incognito/private browser. For more information about adjusting browser settings see: https://support.panopto.com/s/article/How-to-Enable-Third-Party-Cookies-in-Supported-Browsers