The first penalty call is pretty textbook interference. Puck is loose away from both the LSSU and MTU players, who are both making an effort to reach the puck when Henrikson makes the infracting hit. From the first angle in the video you posted, contact looks like its initiated to the shoulder as Henrikson turns into the hit to lessen the angle and soften the blow. Presumably because he realized that the puck was not there at the last second. It also looks like the Tech player tenses up and dips his head right before contact, but kind of hard to tell without slow motion. The second angle shows simultaneous contact with the head and body. The head is not targeted I don't believe, and the LSSU player has a size advantage. I don't believe it warrants a major, and if it did, I would be astonished if the officials had that second angle available to them in replay. As far as I know, there's only the camera above both goals, and the main broadcast camera available for replay. If I'm the down official, my call on the ice would have been interference. And there likely wouldn't have been enough on the video from the first angle alone for me to conclusively say that would have been a major.
The second penalty call is interesting, and neither angle are really very good to see. I'm not going to go to the box score to see what was called, but from the first angle you can kind of see that he leads the hit with his elbow out. Second angle, it looks like he tucks it in to make the hit. I don't think video here is good enough to change a call to a major, or down to a minor either way. Certainly not interference though as the offensive player clearly had the puck. Whatever the official called on the ice is probably what they stuck with. That would be my bet, anyway.
But herein lies the issue with video replay. The second angles on both of these plays look completely different. But as I said earlier, I highly doubt these angles were available for officials to see. I'm familiar with Alaska's setup, and both of the side cameras and the angles right behind the goal aren't available in instant replay up here. And as far as I know, all of the schools use the same set up and software.
I tend to pay attention pretty closely to officiating and I've been critical of some calls over the years. However, I think the league has been pretty good at improving the overall quality of the officiating since realignment given what they've had to work with. A lot of new faces in stripes in the last couple of years.