Accessing my computer Videos, pictures on wireless or LAN connection

I recently bought the Western Digital Media Plus Player.  I am trying to acess my computer files, Videos and wondering if I typically will access them via network shares or media serves.  My WDMP is connected directly to my router with a Cat 5 cable.  Is it possible if my computer is only running wireless to access and play those files.  When I am on both the wireless and the LAN at the same time it won’t let me access.  what about a user name and password if your computer does not have a password set up.   I have firmware 1.3.49 as I was weary of upgrading in case Playon would not work on new firmware.  Appreciate any feedback.  

I am also hearing the term master browser quite alot and was wondering what that exactly means. Thanks.