As the tile says.. I lost 'authorization' for NGC on Verizon.
Click pencil icon under FIOS, click Edit at the top right. Scroll down to NGC. What exactly is shown next to it? Does clicking Rescan next to the channel make any difference?
Strange. It's working for my parents with their FIOS account.
If you go to https://www.nationalgeographic.com/tv/watch-live can you login with FIOS and watch there?
That explains it then. You need to contact FIOS and see what's up with your account that's causing it not to work.
I thinking I rather run out in the middle of traffic during rush hour then call Verizon.. 
As I suspected, on hold for 20, talked for 18 and they have no idea' what the problem is.. "They will get back with me"...
I should have just went ahead and played in rush hour traffic...
If they have an email or chat support line, that might be easier to deal with.
You can also try opening a thread on https://www.dslreports.com/forum/vzfiostv where the higher-level tech support personnel for various cable companies hang out.
Just an update... Still not working, after what seems like quite a few 'technicians' investigating.
I can’t get it to work with Spectrum either. They both blamed each other
Hey thanks for the patience on this. We see that the terms of use changed and no longer allows "live streaming" From Nat geo the browsing portion works fine. We tested and received the same results you did. Nat Wild still allows "live streaming". This update occurred on Sept 26th which aligns with the date you started having issues.
Would love to understand why its working for other Verizon users.. @tmm1
Here is the latest..
Sorry for the confusion, this change is new for us as well. As of the 26th Disney has pulled all the content for Nat Geo to be shown on their Disney+ program. This is not a fixable issue this is a change that Verizon does not have any control over. The messages that are being displayed on the page are from Disney. We thought this was a Technical issue until we had this reviewed. In order to view any of the content you would need to have a Disney+ subscription. Hope this answers your questions
Would love to know if other Fios customer are having this problem.