From that video there's no doubt Cooke hits McQuaid clearly from behind. The right call was made for a five minute major penalty plus a game-misconduct for Cooke.
Now the big question becomes: will it earn Cooke a call from the NHL for a possible supsension? Cooke hasn't been in this boat since he elbowed New York Ranger defenseman Ryan McDonaugh in the head back in March of 2011. So, by the letter of the law for the CBA, Cooke is not considered a "repeat offender" due to the last offense being more than 18 months ago.
Still Cooke won't (and shouldn't) escape his past. When he makes a bad hit like this, he's not going to get any benefit of the doubt from officials. And, truth be told, he doesn't deserve it, because he's earned his reputation, even if he has made a real effort to change his game.
We'll see how the league handles it, in my opinion it wasn't a truly vicious or unusual hit in this day and age, but if the league rules to suspend, I don't think anyone can be too outraged.