Hey guys,
I had the same problem last week when I got my new iMac & used iMovie HD. I got a message saying that the frames were half sized (though I couldn't see anything). I re-connected the cables from both ends, made sure the vcr was set to the proper setting, selected SP or SLP, unplugged the Dazzle bridge & powered on again. Got the camera connected message, as I did the first time, selected play, but no video image ... waited a couple of seconds and then it worked. It seems that I had to select play & import then de-select them, wait again for a second and then try to capture ... go figure. I've used it a couple of times now and it's worked fine. I think I also flipped the toggle switch on the Dazzle unit once it was connected to iMovie & I think this also worked ... can't remember for sure, but I think this also helped straighten it out.
The Dazzle bridge DOES work with Tiger & iMovie HD.
Let me know if this helps.
Take care,
Brent