Is it possible to learn a martial art effectively without going to a class for example reading and watching DVDs and books?

Yes i just fight with instinct and i found out that my instinct fighting is Jujutsu.

Yes its possible but very rare though lol.

There are many Elemental martial arts which demand a period of meditations where one imagines themselves fighting ones self continuosly to develop an internal image of the flow of the select art. This is also our main form of prayer.

If you are already trained to an advanced level, then books and DVDs will allow you to learn more and become more effective, so there is a conditional yes ... but, if you have no training and want to start learning, then NO ... Mastery of a martial art is a gift that must be handed down from one who is already a master ... "monkey see monkey do" is no substitute for the shared wisdom and guidance from a skilled martial arts instructor. While many moves may be partially learned just by watching, the subtle internal aspects are invisible because the camera for a DVD can not show below the skin or into the thoughts. The vast market of martial arts training books and DVDs are seldom aimed at the beginner simply because a beginner has no foundation yet ... also, a beginner does not yet have the needed skill to verify his/her own accuracy while trying to practice what has been seen/read. While in a class, the instructor will guide the student and correct any minor errors, thereby giving the gift of mastery and a deeper understanding through actual touch and detailed explanations.

i do shotokan karate at classes and its awsome fun. But yeah you can do from books. Our Sensei named Sensei Ray Dalke made a dvd on our karate. hes kinda old but hes sick at his stuff

NO ! you cant 'EFFECTIVE' marshal arts at home because there are some moves which require administration to complete else you would break one or more bones or cause any damange to your body so i advice you to dont learn it at home.

PS : you can learn basic marshal art at home :)