Thanks to Germany's Computer Spiele Museum a rare piece of history is now available online: a 1973 demonstration by Ralph Baer, the inventor of home video games, about the potential of a multimedia set-top box.
If you'd simply like to see the only existing footage of Ralph Baer and collaborator Bill Harrison playing with the "Brown Box" video game unit they designed together, that starts at around 6:48, and is a delight in itself ("Well, here we are, playing ping pong when we ought to be working."). But the rest of the video shows just how ahead of their time Baer and his team were.
Using technology available at the time ("We've tried to cut out the blue sky dreaming, what we'll show you today are concepts and hardware that are practical right now.") Baer demonstrates a concept for something akin to an all-in-one multimedia box that plays games, lets users shop by mail-order, has educational components, and even pay-for-TV applications.
Without the use of microprocessors, these applications were extremely simple by today's technology, and required broadcasters to dedicate air time to specialized programming, but what Baer was able to squeeze out of such limited technology is astounding.
At one point, Baer even suggests that the games themselves could be provided by advertisers, making this video perhaps the first documented suggestion we have of ad-supported video games, barely a year after the original Magnavox Odyssey (the first video game console, which used technology licensed from Baer's patents) was released. It would appear that ad-supported games were around, at least conceptually, from the very beginning.
Apparently the demonstration didn't inspire any partners for the "All Purpose Box" (Baer's book doesn't even make mention of it), but as a piece of history, this video is priceless.