I have kind of a stupid question but I figured I might as well ask it on this site because of the great insight I have been getting. I like to fish a lot of soft plastics and have had great success. However; I have seen in fishing videos the angler notes that you must let it fall on slack line. What exactly does this mean? I usually reel slow and allow some line to not be directly tightened while it falls, is this the same thing? Thanks

I think what the video anglers are telling you is that with slack line the lure will fall straight down. With taut line it will fall and pendulum back toward you.

when the say let it fall on a slack line, its so that your bait falls straight down. say you cast right next to a stump, with slack line you bait will fall straight down because there is no tension on the line, but if you have you bail closed and there is tension on your line, the deeper the bait falls, the closer to you it will get because there is not enough slack in the line for it to fall straight down. its good to have the slack line that way the bait stays right where you casted, in "the strike zone" 

I do this slack line thing with split shot rigged worms then I become a line watcher for line movement when the bass takes the worm.

 

With my carolina rigged senko I keep the line snug as it falls to feel a strike as it falls. I do lose some casting distance this way too.