The recent newbie belay thread made me remember the set of very helpful videos the DAV created teaching device handling and general belay skills. Even the best device won't help if you don't know how to handle it. Covers everything from tube/ATC to Grigri and also soft belaying, weight difference etc.
https://www.alpenverein.de/Bergsport/Sicherheit/Videos-Climb-Safe/
