Issue
When showing a DVD in Zoom Rooms, the screen displays a grey block rather than the content. Audio is sometimes (but not always) heard.
Cause
The video is failing to display as the content uses HDCP protection. HDCP is a type of Digital Rights Management encoding intended to prevent piracy by providing an encrypted tunnel between an output device (Blu-ray player) and the receiving end (a computer screen or media center).
Possible Resolution
Try playing the DVD using VLC Player instead of the media player provided by your operating system.