The extra bandwidth argument is the one that may justify 50 gigs to me. I still see problems with the format though. There's a BR insider on AVS who says a full 80% of BR titles will still be 25 gb, making the "the typical BR title will have 66% more space than HDDVD" claim rather dubious to say...
I think that's too rare a circumstance to base a video format on. Can you name more than a literal handful of films (out of 100,000 or more) that are very long and don't have a natural, intended intermission?
I think there wouldn't be much demand for such a thing. Name any other extra long movie without an intermission (in other words, naturally splittable across two discs). I also question whether more than a handful of people want a simultaneous HD video commentary.
The problem is, this is a LONG movie, and that in combination with the space hog MPEG2 means that it's not a sure bet that it will look amazing, even with BD50.
So the MPEG2 monster is still alive, doing what I feared: Eating up BD50 space just to get to where they could have been in the first place with 30 gb and VC-1. Keep in mind this is a 3 hour, 42 minute movie, which means that the use of MPEG2 is going to fill up an awful lot of that 50 gb, and...
A BD50 title is announced at last, which is what I've been waiting to hear, but the extra space seems to be used for the extra long running time, instead of extra bandwidth/bitrate, etc. I'll only be really impressed if the typical BR title uses 50 gb, not 20% or less as indicated by a BR...