Among the performing arts, dance still shows up on television only infrequently, despite considerable strides made over the past decade. One result is that whatever is shown acquires a certain treasurability, without regard to its merit either as TV or dance, merely because of its rarity.

As it happens, the new, hour-long segment of the "Kennedy Center Tonight" series, airing on Channels 26 and 32 at 9 tonight and featuring the Dance Theatre of Harlem performing "Firebird," is worth watching because DTH is one of the nation's finest ballet companies, and because ballerina Stephanie Dabney is quite spectacular in the work's title role. It is a shame, though, that the program couldn't have risen above the mediocre.

The first half--devoted to profiles of DTH co-founder-director Arthur Mitchell, designer Geoffrey Holder, choreographer John Taras and the "Firebird's" dance principals (Donald Williams as the Prince and Lorraine Graves as the Princess, along with Dabney)--is the worst offender. It's like a recipe for anesthetizing the viewer with a video technique at cross-purposes with its content--the medium massacres the message. The operating principle, geared to people with the attention span of 4-year-olds, seems to be: At all costs, let's not do anything linear or logical. The editing is cut-happy, and the footage dwelling on Dabney, Holder, Taras, etc., looks as if it had been shuffled like a deck of cards. Since faces and voices are seldom identified, it's often impossible to tell who's who and what's what unless you know all beforehand. And though the "Firebird"--its production, its rehearsal, its dancers, its choreographer and designer--is the focus, no one bothers to tell the story or describe the characters until this entire "documentary" mishmash is over. Even for the TV generation, the informational jumble is a bit much to handle, and the effect is to dissipate, rather than galvanize, interest.

The performance segment that follows, which is an improvement but not by much, was directed by Kirk Browning, who's had lots of experience with dance and should have known better. Some of his strategies, as in the scene with the monsters, do succeed in heightening the melodrama, but mostly the hyperactive camerawork just fragments the choreography. Not that it's any great loss--Taras' dances are eclectic, competent and ultimately boring, and Holder's neo-calypso designs are jarringly out of key with Stravinsky's music. The company's "Paquita" or Holder's own flamboyant "Banda" would have been far preferable choices. So be it--we dance fans take what we can get; but it would be nice if such opportunities were all used to maximum advantage.