2 Plays

[MJT]

Just watched the videos and here is my take.

No foul in play 1. He is engaged at 2 yards and his forward momentum takes him to 2.5 yards after the D-lineman gets by him. This is why it is critical to see the whole play. We have a the same problem when we work 3-man for MS games in that the U has to drop back when there is a pass instead of stepping up to the LOS.

No foul in play #2. It looks to me as if although the blocker puts his head down, the initial contact is above the waist and then he slides down. This is a 15 yard penalty and you had better be sure if you are going to call it.
Remember, the "when in doubt" guideline for "block above or below the waist" is "above the waist."