Box for Android uses the same Box previewer you see on Box.com. If you are having trouble viewing files, first check the list of compatible file types to make sure your file is supported. The one limitation on Android is that media files cannot be streamed. If you want to view a movie or audio file, you will have to download or open it and view in a dedicated media viewing application.
If you are having trouble viewing larger files, check to make sure have a strong signal or try a different wifi network.