Why are there moving black bars on the sides of some 3D discs?

[that1guystudios]

Originally Posted by fitprod

If they're smart, they'll just package the separate 2D version with the 3D version, as Disney will be doing with A Christmas Carol.

It's not like the studios wont be producing 2D BDs of these films, that's where 99.9999% of their Blu-ray sales will be coming from.

fitprod

I think that packaging 2 separate versions is the best way to go as well.
It's not like it costs them studios a lot more to make an additional disc now that the replication fees have gone down...and I personally don't mind having two discs if they are optimized for different formats, and both are compatible with 2D displays. Heck, I could even give away my 2D copy to a friend or family member. Who wouldn't want a free Blu-ray?