And it prohibits disclosure even after the sale/reassignment was completed? I don't understand the purpose of that, at least not a legitimate purpose.

Sounds like you were on the losing end of some strong arm tactics. Or did I read your comment wrongly?

http://assignment.uspto.gov/#/search?q=7460731 Here is the most recent public assignment of that patent family. It from Flixor, Inc. to Big Tent Entertainment, LLC. http://www.bigtent.tv/