Not sure it's as clear as some make it out to be, and it very well may have been his goal.
I keep clicking on "8:01" on the video full screen, over and over for just 1 second, and you see the puck pick up speed at the exact moment Mess does some sort of wrist flick. It also comes from his direction. I think it all happened really quickly, and that Mess got it on the foreswing, not the back swing, if that makes any sense. And sure, there's totally a chance he didn't touch it. But the video does show some signs that he may in fact have. Just keep clicking on 8:01. Watch the puck pick up speed and go between the goalies legs at the exact moment he does some sort of wrist flick. The other bodies sliding in front wouldn't seem to have made the puck pick up speed or direct in that angle.