Yes, the video was very helpful in that I knew exactly what I needed to do. It was real easy.
I finally did a "clean" install of Joomla 1.5.15, then I installed Quantive template, then the extensions for Rokbox "system" and "content". I then "enabled" both of them through the "Plugin" manager... and guess what? It works!!! The "Member Login" button works!!! Yeah!! Now I'll go back to my "original" site, the one I had difficulties with, and see if I can produce the same results. I'll let you know...
Success!! I successfully got the "extensions" installed (rockbox_system & rockbox_content) and enabled them both on my "live" web site using the administrator/Extensions/Plugin Manager/ and it works!! Please note that this site is being developed...