It has been reported that download helper programs sometimes cause the problem that they claim to be solving. If you have GetRight, GoZilla or a similar download helper program running, turn it off and try downloading again. If that doesn't work or if you don't have any such program running, an alternative download method, FTP, is available for all of the files. FTP is more reliable than HTTP so try the FTP alternative by clicking on the file name in the above table. The NVR filters don't show up on the filters menu.
Several things can go wrong.
Copy the filter files to the plugins directory. See the Installation Instructions for more information about other graphics programs. The plugins directory pointer is wrong. You will get a dialog box which allows you to choose the plugins directory. Note that if you change the setting, it will not take effect until you exit and restart Photoshop.