[benchaney]

When one door was opened it revealed information about the other two doors.

[bigstrat2003]

But it didn't. Before, we knew that one of those two doors could contain either a prize or a goat. After, we know the same exact thing. No information was gained there.

[benchaney]

As a result of how the doors were selected one of them is more likely to contain the prize. That is information.