Providing an unencrypted stream of any kind could violate HDCP. Therefore, Crestron have provided:
"Image preview provides still images (thumbnails) that show the current video being received by an input of a DM NVX encoder. Still images are shown at one frame per second. Image preview supports the maximum resolution of the source and scales the image, while maintaining the aspect ratio. Images can be previewed in the DM NVX web interface and accessed remotely using a web browser. The images can also be previewed on a Crestron touch screen or third-party interface."
I don't know what the HDCP police allow, but perhaps a faster update rate to say 0.25s would be more useful as a preview but still not worth "watching" or recording.
