One more time.
If the video had continued, you'd see that Connolly popped up and jumped back into play.
The WCHA, which has access to far better video than what's shown in the YouTube clip, looked at Knight's hit and determined that it was clean.
It's not that I have great faith in the league to make correct decisions. However, given what happened to UND's Mario Lamoureux (suspended for a minor penalty that went uncalled during the game) and Brett Hextall (tagged with a checking from behind major he never committed), there's no doubt in my mind that if the WCHA felt it had a legitimate reason to suspend Knight, it would have done so.