A few years ago, Barnes & Noble switched from creating their own NOOK devices to using existing (Samsung) tablets with specific NOOK oriented modifications.
Shortly after, they made the move to include support for Google Play on the NOOK HD and HD+ and of course their newer Samsung NOOKs.
Earlier this year, they decided to close their own NOOK Apps section and now only Google Play will be usable to install Apps on a NOOK device.
Previous customers for the NOOK App version of MoviePlayerApp (MovieGallery) will still be able to download and install the app from NookApps, however, because the development area for NOOK Apps is also closed, no updates will be available anymore.
The current (last) version of MoviePlayerApp on B&N Nook Apps works as it always has, with the exception of the build-in cover-search feature. A recent change of Google broke this functionality, but while I do have an update that fixes it, I am unable to update the version on NOOK Apps, so it will remain.
This article on the website,
explains how to manually (its easy, don't worry) add cover images to your movies.