Wake up early.
Trust me, I'm a student too, and I know how crazy life can get (especially when the girls down the hall have something fun to do). The only way I have managed to get in exercise consistantly is to plan to wake up early, go to sleep in my workout clothes, and commit loudly to everyone who will hear that "I'm going to the gym at 6:30am" (so that I have people who will notice if I stop).
If you have a roommate, doing workout videos in the morning might be a problem, but most colleges I know have a gym for students. Might be worth checking out.