Am I making a good deal with selling a DVD that came with a college textbook?

My former teacher sent the class an email asking if anyone wants to sell their textbook with DVD included.



My college textbook is written in and I want to keep it. I had purchased my book for $70.00.



I am willing to to sell my DVD for $20.00.Am I making a good deal with selling a DVD that came with a college textbook?
If you no longer need it, it is probably a worthwhile thing to sell. I've used books with DVDs in my classes and if you've watched the videos, I can imagine that you would not find it useful to reference them again. While the book might have equations you can reuse later, the videos are often motivational. And many segments are also on the web in various places.