Sorry, I didn't notice you were in the UK
I think the main reason is that these sets take time to produce, and they only have so many people to work on these things. TV sets take time, and if we want them done right, it takes some extra time and care
Paramount has almost no control over when Indy comes out, that's up to Lucas and Spielburg
Often times with new movies, the DVD is worked on as the movie is made, I think David Prior said he finished Planet of the Apes about a week after it hit theaters.
Again, the wait on Buffy is because of...