It's similar to the yellow line superimposed on the TV image for home consumption, but it's visible to the players and fans in the stadium as well, under the lights or in bright sunshine.
I'm not sure how I feel about this. From a fans prospective, it's great, but I'm not sure I want the players to see the line. There's no doubt the "yellow line" has been the best innovation to viewing football on TV since they first starting airing games nationally. I'm just not sure if I like the players being able to see it. I guess it just makes the game a little more sterile. I like the fact that it's not perfect now (even with the little yellow line) and sometimes the two don't match up. It just add some suspense to the game. I just think the game could get sterile with the laser lines. Then again, maybe the game becomes more exciting. Either way, I'll still be watching the Steelers so I guess it doesn't matter much to me. :)