From its origin in 1949 to today's showmen and scoring machines, the story of the National Basketball Association, complete with its dynasties, rivalries and characters, becomes available Thursday on home video.

"History of the NBA" (60 mins., $19.98) is a CBS/Fox release in conjunction with NBA Entertainment. Former Los Angeles Lakers' coach Pat Riley does an excellent job as host. At times he's relaxed enough to leave the impression he may be enjoying himself even more than the viewer.

In the first of six "acts," Red Auerbach and Minneapolis Lakers' standout George Mikan reflect on how the NBA was formed in 1949. In those days, Auerbach was coach of the Washington Capitals, who moved to Boston and became the Celtics. The script actually goes back 100 years and salutes the inventor of the game, James Naismith, as well as the pioneers of the professional game in the early 1900s.

Riley is joined by Bill Russell in act two, entitled "Dynasties and Rivalries." This segment is dominated by stories and clips of the Boston Celtics of the 1950s and 1960s, and includes recollections by Boston's John Havlicek and Tom Heinsohn and former Lakers Jerry West, Elgin Baylor and Wilt Chamberlain.

The third segment, "Centers of Attention," is properly co-hosted by Kareem Abdul Jabbar and looks back at his career, including 1971 when he teamed with Oscar Robertson to bring a title to Milwaukee. Vintage footage of the big men includes the play of Willis Reed, Wes Unseld, Russell, Dave Cowens and Bill Walton.

Next comes the pizazz portion called "Showmen," featuring the sparkle of co-host Bob Cousy, Earl "The Pearl" Monroe, Julius "The Doctor" Erving, "Pistol" Pete Maravich and Connie "The Hawk" Hawkins.

Earvin "Magic" Johnson joins Riley in co-hosting part five, "A New Era." This segment highlights the rivalry between Johnson and Boston's Larry Bird and traces a number of contemporary superstars featuring (who else?) Michael Jordan.

The video winds up with "Characters of the Game," including glimpses of Darryl "Chocolate Thunder" Dawkins, Boston Celtics' announcer Johnny Most and former Utah Jazz coach Frank Layden.