The other classic. Really, if you're in Smith, you have to climb the Cliff Bar. Chain Reaction was the second climb bolted in Smith (and maybe North America), the first being "Watt's Totts". Despite this, it received all the attention and was widely believed to be the first. Still a classic and historic climb.
Very bouldery but very short, Chain only climbs about 40 ft. Bouldery also tends to mean that beta varies from climber to climber and this climb was no exception. If you're seeking this video out for beta, I'd suggest paying attention to the holds and features so as you know what to expect. There's a good chance my method only works well for me.
The Trickery? This video isn't a send. I had sent it a week prior but never got a video of it or Heinous, so the day I left Smith, I ran out to the Dihedrals and asked for a belay for both to get them on film (thus why I had dialed beta). Unfortunately, I slipped up at the crux move. Thought I'd test the editing skills a bit and spliced out the fall.