I have found, at least with Android devices, the same apps that play the video will play your music files. Some will even access your pictures as well. Make sure the Hub is setup properly (Read the Manual) for Apple devices as I'm almost positive there is a setting of some sort for them. Music should be in it's own folder, pictures in their's and video it it's own folder. It'll help if you have a music folder off the root folder of the Hub. This applies to the other media too. Inside those folders you break it down as you want. Most of us for video do:
Movies (In root of Hub)
Action (dump all movies don't use a folder for each movie)
Drama (Same as above)
Comedy (Same As Above)
I think this is how most of us do music
Photos or Pictures you can pretty much do as you like I think....
I use my Hub for video ONLY no pictures or music. I keep music and pictures on shared external drives on one of my PCs. Music on one drive Pictures on another. But that's just how I roll, as they say. All of it can be accessed from my tablet, phone, WDTV units, Smart TV and PCs as all the drives are shared in Windowz.