from reading the scripts, it seemed that RR wrote the missing reel into his script and QT actually had to cut footage out of DP for the missing reel effect. Can’t tell on the timing, but a real missing reel would be around 16-20 minutes. I doubt RR actually shot his missing reel but it’d be a nice dvd easter egg if he did. As for DP, well we’ve seen footage in the advertising that has been lost via the “missing reel” so I’m sure we’ll get some of that on the dvd.
Overall, these are just guestimates but I would say 5 minutes from DP and 15 mins from PT.