This is yet another video extolling the virtues of using Roxul "Safe and Sound" insulation. Because Rockwool is fire-resistant, you can insulate with it up to the cans that support the recessed lighting without fear of overheating the lights (and burning out the bulbs) or igniting a spark. However, any time you open a hole in your ceiling, you invite the opportunity to transmit noise between floors. Remember: if you're going to spend money on drywall, get something like QuietRock or Supress that dampens noise. This is your one chance to get it right – don't cut corners on the materials and regret it later!