L & S Video at
http://landsvideo.com/ is the place for you for sure.
It has a really nice collection of art DVDs with lesson plans for students of all ages, from K right the way through to college level, and a great collection of African American artists at work in their studios, like Romare Bearden, Faith Ringgold and Jacob Lawrence.
Many of the videos also come with study guides for all sorts of fun and exciting activities you can do at home, or in a classroom or group setting.
The study guides are about 16 pages each and the ideas can be adapted for whatever age group you are teaching above about Grade 3.
Then they have the I Can Fly Series of
art appreciation for kids videos for K through Grade 4 that features many of these artists, and I think I Can Fly 4 is all about African American art.
You don't say what age you are teaching but there are 25 videos mostly on African American artists, so I think you will find something there to suit your whole class.