There are many instructional videos about Shotokan. Absolutely the best Shotokan DVDs are produced by Joel Ertl and Anita Bendickson, at their web site http://www.karatevid.com.
I especially recommend the DVD Shotokan Karate: Heian Kata 1-5.
The special strength of these DVDs is Ertl's and Bendickson's crystal-clear explanation of each move of each and every kata in the Shotokan system. No one else has even come close to this level of instruction in a DVD course.