If "it's actually probably easier to watch than play" and there is a dearth of testers, perhaps some kind of adjustment should be made to RBN. Recruit people without XNA membership who can vote by just watching videos and make their votes count half as much as regular playtesters.
Honestly, the only thing that ever held me back was sheer inconvenience. If I could just turn on my Xbox and test the videos without incorporating my computer I would gladly pay the 99 a year fee, even if I had to still rebuy tracks I want to keep scores, play multiplayer etc. I can't really play the drums where I live now either which I hate.
But my Madcatz keyboard just ruined a year old laptop because I tried to hook it up using something recommended on these forums from Amazon, as is.
That would still require coopoeration from Microsoft. You can still watch videos and give feedback if the group puts their videos up (and some groups like TAG put up videos of most of their drafts specifically for this purpose), but anything that would actually let you submit official playtests or reviews without and XNA account needs Microsoft and Harmonix can't do it on their own.