On Livescope .... the feed is constant, out to the distance set, so that's about as "live" as it gets. Unlike other sonars, where the screen is "moving" and what's being displayed is mostly "history", Livescope isn't recording that history, but showing the "present" (within the range/width of the sonar ping signal). Basically it's the difference between a stream of snapshots and a underwater camera feed.
My buddy, slabeye, has one and I've fished beside him and watched fish come to the bait ... sometimes hitting, sometimes not. He's also told me of some of his experiences with it, like when a school of Crappie are hanging around submerged timber and move to the far side of that timber when one of those fish are caught.