Description of ニコニコPlayer【非公式】
It is a simple app that can play videos of Nico Nico Douga
■ Remaining restrictions
・ You cannot log in if you have enabled 2-step verification for Nico Nico Douga.
・ There are videos that cannot be played or may not play correctly depending on the model you are using.
・ Video playback other than mp4 is unstable
(If Adobe Flash Player is installed, you can also play flv format videos.)
・ Use device storage to cache videos
The pace of development is slow, but I'd be happy if you can be patient.