VLC (VideoLAN) is definitely my favorite media player. I primary use VLC when I watch a movie when it comes to music I use iTunes from Apple.
Most often I use VLC on my MacBook Pro as it is the best portable device to watch a movie on, but watching a movie on the iPad is also recommended.
It is possible to watch a movie on iPad if you buy (it costs 1.99 US $) and install VLC Streamer on your iPad and afterwards install a VLC Streamer Helper which is a small application that will run on your computer where you movie collection is located.
The perfect setup would be to install the directly on your NAS device but I have not succeeded to do that, so I have installed the VLC Streamer Helper on my Apple Mac Mini where I have mapped my movie folder that is located on my NAS. It should be possible to install the VLC Streamer Helper on a Linux box like a Synology NAS.
With this setup it is possible to browse and launch movies on my iPad placed on my NAS.
I agree it is not the perfect setup but it does work.
My Mac Mini and my Synology DS211+ is running 24/7 so why not make the most of it.