Yes, i agree! An instructor can actually see you and correct moves you are doing improperly. I use taped instruction myself sometimes, but I originally got it to supplement my classes, which met only twice a week and there were frequent breaks as this was through a college schedule.
I've been thinking of other ways i can reduce my stress. I wish i more disciplined to actually DO them. A lot of stress reducing activities are a slow investment: like yoga, exercise and meditation. Doing it once only gives you a little benefit. Doing it habitually, though, gives you great advantage.