I called Amazon last night to ask about the format. The girl not know but their return policy is very good. So, I bought both, The Avengers movie and the LotR trilogy.
I also put the first 3 seasons of Babylon 5 on hold at Future Shop. They were on for $9.99/season!
I hope I get the chance to watch them again soon. ..and I wish they had the last 2 seasons as well.

BTW,
I called Amazon by way of their website last night. I was in contact screen and a button on there said "call now". I clicked on the button and my instantly rang! I just picked up my phone and someone was on the line in about 20-30 seconds. Pretty amazing technology.
The greatest things in life are not things.