The first immigrants to our hemisphere arrived on foot about 15,000 years ago over a land bridge that then traversed the region between present-day Siberia and Alaska. They walked thousands of miles and hundreds of years, over the generations, to settle the Americas, and it may be something of a commentary in itself to note that we can learn about this migration on television, sitting at home and not moving a muscle more than those needed to flip a dial.

This saga, ”The Search for Ancient Americans,” is the first episode in the new season of ”The Infinite Voyage” series on public television, to be seen in this area tonight at 8 o’clock on Channel 21 and tomorrow at 9 P.M. on Channel 13. The series, produced by WQED in Pittsburgh, is in the best tradition of educational television, an observation that may unfortunately sound more like an accusation than the commendation it is intended to be.

This first episode, written and produced by Stephen Eder, with N. Scott Momaday as narrator, is a worthy project for several reasons. For one thing, it informs, and for another, its information is passed along in a creative way. There is no monotonous classroom lecture and there is no stultifying concentration on scholarly minutiae that can so often deaden a visual production. Scholarship is by no means neglected, but there seems to be a realization that video is quicker than the printed page and that the eye is not the same for both media.