From the look on the video the "manual" tension pulley on the Whipple itself looks like it needs to be slid over to the drivers side some more. Usually that pulley is almose all the way to the drivers side in the slot.
Rich, I agree with your observation too and I discussed this with Bruce last night. Shadowman & Dustin both advise to have this idler over as far as possible.... so this is something that should be done at some point. I'm not sure this is the culprit, however, as the OEM belt tensioner is still applying relatively linear tension, whereas the idler will improve belt wrap (less slip chances at higher boost).
Bruce, in seeing/hearing the video..... that chirp is annoying as hell!! I better understand the frustration you expressed last night!!
Are you reasonable sure that it is the SC pulley? It could be one of the other pulleys.....