Thanks. I think I figured it out. Thought i'd post what I did for others in the forum
From the player file servers page, clicked on the "+" and enter the IP address for your NAS. If you have password protection on your NAS, enter the login and password. The port number 21 was pre-added by the application. Under Title I listed it as "link station"
Now I could see the NAS but could not see the "share" folder which is where my media files are located.
From a web browser, enter the ip address of your Buffalo NAS and login to their web manager tool. Navigate to shared folders-> shared folders setup. Click on the folder name that has you media. In my case it was called "shared". This will bring up the "editor" for the shared folder. Under shared folder support make sure "FTP" is selected (I actually enabled all 4 formats)
When I returned to Oplayer, I was able to navigate to "link station" and then see my "shared" folder with my movies which I was able to play.
A couple questions I have yet to explore
1) Is Oplayer downloading the movie to my iPad and then playing from there or is it streaming?
2) what are the advantages of downloading vs streaming a movie
3) i noticed the aspect ratio of the movie looked different (faces looked squished sideways). Not sure if this is a 16:9->4:3 aspect ratio problem or some other issue.