The ‘browse file list’ (BFL) option can only be used on ADC hubs. That’s why the option is ‘grayed out’ on NMDC hubs. (Yes, I’m aware of BFL showing if you are in a NMDC hubs - It has been fixed though.)
What BFL actually do is following: Enable you to download parts of a file list you want.
If you select ‘get file list’, you download the user’s entire file list. This means that you will see the ‘Knoppix’ directory and the ‘FreeBSD’ directory. (Fill in ‘Knoppix’ and ‘FreeBSD’ with another directory name.)
If you are looking for only FreeBSD and don’t care about Knoppix, you still have to download the information about the Knoppix directory. Thus, you use space on your disk and precious bandwidth.
With BFL, you will not download the entire file list. You will only download the parts you want to view. So if you want to look further down in the ‘GNU/Linux’ directory, you don’t have to download the directories about Slackware and Debian but instead go directly for the Fedora directory. If you then decide you want to view the Slackware directory, you can of course.
The point is: There is no need to download huge file list containing directories you don’t even care about.