According to WD Support the app, as implemented on iOS, uses WebDAV and hence is limited to streaming files smaller than 4GB. WD Support also says the app is not intended for ‘full on’ streaming.
It would be nice if it used DLNA so as to remove this limitation.
I argue this makes sense as storage space on the iPad is very limited and one of the obvious applications for the app is to stream files stored on a MBL.
The limitation was probably not an issue when media shifting from DVD, but HD content is now typically 4-6GB and sometimes more.
I have now removed the app from my iPad and am using the FileBrowser app from Stratospherix. That app is also not intended for ‘full on’ streaming, but seems to deal with it quite nicely. However, it would be nicer to use a WD app to work with a WD product, don’t you think?