Book sales are a useful indicator of interest in a particular technology.
I found Bruce Epstein, O'Reilly editor and author of Director in a Nutshell and Lingo in a Nutshell and more recently, the editor of an upcoming book on ActionScript , Flash's scripting language. Your implication is that Flash suddenly burst on the scene out of nowhere. Macromedia has been making strategic alliances for years and Flash's popularity has been growing steadily. The increased book sales in 2000 reflects its emergence into the larger public consciousness. There were enough big sites, such as Disney, using Flash that it has gained wide acceptance.