If you've bought a Bang&Olufsen BeoVision / BeoCenter AV5 system, you were probably looking for the built in CD-i system. It appears that B&O released a version of the AV5 including CD-i and a version without CD-i. But in fact, both versions have the CD-i player inside, as well as hidden controller ports. The Bang & Olufsen BeoCenter AV5 was a design television with a built-in CD-i player. These were sold for a longer period than CD-i was actually supported by Philips (Philips stopped support around 1997). It seems that there are B&O AV5 units that do not advertise to have a CD-i player on board, without any controller ports on the back but for the rest look and feel like the same unit. A few owners of these units confirmed that these tv's actually still have CD-i compatibility on board that can be activated via a secret menu.
CD-i member Muh Mullet even has some more info on this: "The controller port is also there, under the plastic, take off the back and you'll see it. You can also install a DVC there, it takes the smaller one found in the 450 and 470 models. If you take off the back of the tv. My friend had one like yours, full CD-i functionality, but all hidden. He found the controller ports under the plastic rear cover, drilled two holes, and installed a DVC. It seems toward the end B&O were still using CD-i players in these tv's, but didn't advertise them as such, and sold them as having a normal cd player built in."
[Thanks, Steep Haywire, Muh Mullet]