When we debriefed that evening, I felt pretty good about the results--we could really see what was happening for the most part. The instructor was critical, though. He noticed that on a number of occasions while I was filming I had broken trim, and I was essentially reprimanded in front of the students for doing so.
Sorry to hear about your bad experience. I had the opposite experience whilst filming a Fundies class. I was told repeatedly that my job was to film, and that looking pretty wasn't the most important thing. I'd like to think I looked pretty, but there were definitely a few moments where I was doing a sea lion impression and there was nary a comment afterwards except a thanks-for-filming and a suggestion about backing up more on the ascent to get everyone in from fin tip to fin tip.