How do I find 'new' files?

I’m a newbe here, sorry, if this was dealt with already.

Part of my home network are WDTV HD Live and a MyBook as NAS-Server.

Now when I copy new media files to MyBook, shared videos, I don’t know how to rapidly refresh the content in WDTV Live.

I don’t yet see the new files even after switching off and on the WDTV once or twice. Then, only much later, I find them.

How does the refreshing of the content data base take place, how can I accelerate it?

It’s annoying.

You have the WD live connected to your network via the eithernet port, you have to be ceratin that the WD Live has the correct permissions to see the other NAS devices or shared folders on the network.  If the MYbook is connected to the  WD LIve, there is no sharing or permission settings to set.  

Thanks.

It is as you say, and at some time the newly added files can be browsed.

But why does it take so long, how could I enforce the refreshment?