Threat models for embedded devices

Of course, if that HDMI television supports some sort of DRM, then the manufacturers will probably have a particular threat model imposed by the DRM providers: a DRM-hating owner who sends an exploit to their own television in their own home over HDMI, then changes the data source.

Could they get access to get the unencrypted data stream? Could they come up with some way of getting that data stream out of the television at a reasonable bandwidth (for example, by pointing a video camera at the screen)?