[jitter] Flickering video with quicktime grab and jit.op

I'm using jit.op to show a quicktime movie triggered by audio through msp peakamp~ and I want to blend that with a live quicktime grab via jit.xfade.  As soon as I start the grab, the viewer from jit.op starts to flicker.  I've tried to lessen the compression quality on the grab, and slow the metro, but it still flickers.  I've been using max/msp/jitter only for about 2 months now, hence the constant roadblocks I guess!