I have been using NLS Web Braille books for nearly two years.  Until
recently, I downloaded these files with Internet Explorer.  I had set
Folder Options in Windows to recognize brf files.
I have now switched to Mozilla Firefox for browsing.  Firefox isn't as
accessible as IE, but it is much faster, less subject to hacks and has
tabbed browsing.
I have been unable to get Firefox to recognize brf files at the NLS Web
Braille site.  Even though it downloads from other sites, when I click on a
brf file representing a book volume, it just opens the volume on screen.
I would be interested in hearing from anyone who had used Firefox with NLS
Web Braille.
Richard Wright