Analog delay lines are usually used to make very tiny adjustments to timing, generally no more than a few microseconds. They are used to align parts of a single video signal when it's component parts have taken different routes through processing circuits. I've never heard of them being used to align different video signals.
I assume you are referring to synchronizing different video sources, for that you either have to lock the sources to a single timing reference (Genlocking) or individually digitize the sources then replay them simultaneously using a frame store.
Brian.