I am under the impression that was Andrew Georgitsis in the video (could be wrong) and if it is, I'm fairly certain he's experienced enough to know he was moving his fins.
I'm in agreement with you. I've just noticed that now I'm doing things automatically that it used to take concentration to achieve. The little adjustments just start to come automatically with time. Whether AG (or whoever) realized they were moving their feet or not, I'm definitely sure it was an automatic motion that took little effort or concentration.
Tom