I would not call that link "well documented" it refers to a couple of people.
Never had any playback problem on my nexus 7 with other video playback, but i cant comment on the new lightbox app as the code i got emailed for a free month says it is not valid.
got a link to blame that on as well?
I'll freely admit that we haven't tested on 2013 Nexus models - since testing across every single device in the Android universe isn't really realistic. We'll take it to the devs and see if there's anything we can do, but clearly something isn't quite right on this device and Android 5+.
I am guessing you received the code over a month ago? It's only valid for 30 days...