Please find my responses further below in-line with your queries.
Before that a general note: We would like to promote the concept of always-on 1:1 customer engagement and move away from the term "campaign" when referring to the outbound runs scheduled via Next-Best-Action Designer. These are so much more than campaigns. The always-on outbound approach allows you to define a single customer engagement policy, shares a common interaction history and learns from customer behavior across all channels.
Answers to your queries:
Issue 1: Campaign execution does not reflect academy course materials
In the exercise system, the segment used for the starting population is configured to select a random sample of 100 customers. (see Options tab in the segment). Every time the segment is run, either manually or triggered by the outbound run, a new set of customers is selected who are likely to qualify for different actions than the one shown in the exercise steps. This discrepancy is expected. A note has been added in the exercises about this.
Issue 2: Dynamic email substitution did not occur
This issue is fixed. Please request a new exercise system to experience the fix.
Issue 3: when reviewing campaign runs in NBAD, I get spurious caution message
This is a product issue. We will share this feedback with engineering.
Issue 4: after 15 minutes, video never came available.