Update 1: Reader Paul B, who also happened to chair the group that wrote the MHP PVR specification, writes to inform us that "there is no such flag as standard in the spec. Philips could add one as a Philips-specific flag but it wouldn't apply to the other manufacturers. Secondly, as currently specificed there is no way for an MHP application to take control of the channel switching function, so changing channels always works." There you have it folks; it seems that all your MHP-equipped gear is safe -- for now.
Update 2: Royal Philips Electronics, ever mindful of their Engadget-reading customers, had this to say in a note to us: "(Philips) filed a patent application, as yet not granted, that enables watching a television movie without advertising. However, some people do want to see the ads. So, we developed a system where the viewer can choose, at the beginning of a movie, to either watch the movie without ads, or watch the movie with ads. It is up to the viewer to take this decision, and up to the broadcaster to offer the various services. Philips never had the intention to force viewers to watch ads against their will and does not use this technology in any current Philips products, nor do we have any plans to do so."
[Via New Scientist]