Students can use materials shared in ILIAS for course purposes in the corresponding course. It is however prohibited for students to copy, use, sell, transfer, publish or otherwise share ILIAS material they have access to for other purposes. For example, it is not permitted to share teaching videos via YouTube. It is a different case, however, if the copyright holder has given his/her consent or copyright limitations/licencing agreements allow such usage (e.g. as per § 60a or § 51 UrhG).
