This is a really good question and I would love to find the answer. I have a feeling that because iTunes hasn't been updated since the release of Aperture 3, we are stuck. We currently cannot get videos that are in our Aperture projects onto our iPhones via iTunes sync. I just ran into this myself as I was cleaning up my iPhone photos. I've recently thrown ALL of my videos taken on iPhone and DSLR into Aperture, and now I can't get them to sync. Its pretty unfortunate because even the videos that I've taken with my iPhone won't get sync'd back and that means I HAVE to keep them on my iPhone's Camera Roll. I assume this will get addressed sooner or later. I guess this is just one downside of early adopting...