Leonard Bernstein, the man who, among many other things, has done more for classical music on television than anyone else, appears tonight in yet another video guise. He is a piano accompanist for that matchless mezzo, Christa Ludwig, in an hour of subtle, introspectrive Brahms songs, or lieder as they are called.

This is not the sort of material that normally reaches the television screen. Indeed, one does not recall a comparable hour on television (Channel 26.9 p.m. with stereo simulcast on WETA-FM). Andre Previn has done some piano accompanying on his program, but these were altogether more informal occassions than the taping of these 17 songs in the Tel Aviv Museum right after a formal all-Brahms concert there by Ludwig and Bernstein.

Heretofore, the larger musical forms - particularly ballet, opera and symphonic music - have commanded the television screens. But the larger the spectacle, the more that may be lost by the selective camera. In particular the visual sweep and depth of dance often suffers.

But in lieder, the opposite can be the case. As Ludwig suggests during one of three interview segments strewn through the show, the lyric words of the lieder are crucial to the experience. "If one doesn't see the eyes and mouth, one doesn't understand," she observes. And that is easier on these tapes than from, say, Row DD of the Kennedy Center Concert Hall.

Beyond literal translations from the German, too many nuances are lost when tampering with the original. The solution on this show is to have Martin Bookspan give precis before most of the songs. Subtitles would distract. Then look at the expression of grief that passes over Ludwig's face as she reaches the emotional peak of "Death Is the Cool Night" and you won't have to know a syllable of German to comprehend.

By the way, for those who would like to go further, all of these songs were recorded live at the preceding concert and released on a Columbia LP, along with texts and translations.