I fail to see why Pihlström was given anything else than a minor for interference. Pihlström didn't attempt to cross-check Holzer to his face, he went for the unnecessary hit and then Holzer stumbled before Pihlström made the contact. The play didn't look dangerous and Pihlström didn't have much speed at the time of the contact. You can watch the video yourself.
In an ideal world that play would have been two minutes for holding to Holzer and that would have been the end of it. However, it wasn't an Pihlström lost his cool and went for the unnecessary hit, since Holzer didn't have the puck. That's two minutes for interference. Then Holzer loses his cool totally and is about to start throwing punches while Pihlström is probably thinking, "Well, that escalated quickly". Pihlström clearly had no intention to injure or harm Holzer and he didn't.
How on earth did Pihlström get two minutes for roughing and two minutes for cross-checking is beyond me. There was no cross-check and there was no roughing either. Only an unnecessary hit, for which the proper call would have been two minutes for interference.
Huh?
Yes, Pihlström was most definately trying to cross-check Holzer, in a big way at that. He took his stick with both hands and lifted it towards Holzer, there is no way you can lead a normal hit with your stick in front of your body. That was as clear cut a dirty action as it can get, it was nothing but a revenge play.
Holzer only "lost his cool" when Pihlström made his completely dirty and unwarranted move. That is blindingly obvious in the very video you posted. In fact, Holzer kept his cool when you consider what actually happened. He could have pummeled Pihlström for what he attempted, but he clearly held back once he realised that Pihlström turtled and wouldn't back up his acts.
Holzer should have gotten 2 minutes for taking down Pihlström, but Pihlström is very lucky that Holzer got out of his way when he attempted the cross-check, because if that thing lands as intended, Pihlström is out of the game. The way it worked out, it was merely an attempt, but even that is enough for a penalty. What happened afterwards wasn't all that relevant, Pihlström held down Holzer, Holzer didn't really punch him, at best that's two for both.
As the play turned out, it shouldn't have been a powerplay, it should have been either 2 for both or 2+2 for both. Whether things would have been different if the refs had called the penalty on Holzer (leading to no cross-check b Pihlström) or if Holzer hadn't evaded the cross-check (possible more than just 2 for Pihlström) is moot, as it didn't happen.