That's an old post, it was working a few weeks ago (last time I checked). If I can use my Vidgo credentials to log into the TV Everywhere version of the NFL Network (NFL Network | Watch Live Football Games & Events | NFL.com) it should work in Channels.
Can someone from Channels Support verify that the NFL Network and NFL Redzone (when the season begins) is still accessible or not using TV Everywhere? Both used to show up in the list of available channels for Vidgo, and other streaming services.