If you are interested in online self defense training, online self defense courses, or anything else to do with learning mixed martial arts or krav maga self defense techniques online, you are in a great position.
There are many experienced martial artists out there putting out quality online self defense videos and training manuals. Depending on what you're looking for, you can find self defense programs for beginners, or you can choose something more oriented towards people with experience in martial arts and self defense.
Learning online is a little different than doing it in a dojo or martial arts center. No, you do not get one on one training, and I would not say you should just depend on what you find online to learn self defense. But it can be a good supplement to use training videos and online self defense courses.
Really all you need to learn online self defense techniques is to find a suitable method - usually videos are good. Either you can order dvds and practice moves in front of your TV at home, or just download self defense videos and watch them from your PC, then practice them on your own.