Since NL2 is not registering the default opening program for the track extensions, they're appearing as hidden files. So from what I've seen. I don't have nl2 but from the join me sessions we enabled see hidden files and they were there. So,have it display hidden files and they'll popup. Mike reported a solution to this in the NL2 thread which should solve your problem its quoted below.
Originally posted by Mikey
It looks like some of the issues that you guys are having downloading and opening NL2 files on the site, is that NL2 does not register the default application for it's file extensions. Atleast on the windows 7 and 8 machines that I tested.
Nromally you can manually register the file extensions to the application by running:
%windir%\system32\control.exe /name Microsoft.DefaultPrograms
From a command line, select associate a file. But Nolimits does not seem to register anything at all.
This is a problem for websites that offer track sharing, it will make it harder for the end user to run tracks until its fixed.