^ I was referring to this:
Looking up the video that could fit on the disc, a Blu-Ray can hold 9 hours of HD video or 23 hours of SD video. Assuming 5 episodes per disc, which is the going rate on my Blu-Rays for the Prisoner, you could have roughly four hours of HD video (five episodes) and still have room for 10 hours of SD video.
So you could easily fit five HD episodes (pretty standard for Blu-ray releases) along with their 5 original SD counterparts and still have room for some special features, without needing to add so much as one extra disc. But even if it required adding, say, one more Blu-ray disc to the collection, that has to cost Paramount all of 10 cents. If the content is already there, and doesn't have to be edited or changed in any way, just sticking it on a disc costs virtually nothing.