[V5V]

Just don't use a Blackmagic Intensity Shuttle as the capture device. For reasons that Blackmagic considers valid, it won't lock to sync from VHS.

I use an old Canopus 110 that we used for video output from Pro tools way back when. Now it takes video in instead of spitting it out! It's connected to the Mac with a Thunderbolt to Firewire adapter.