That series was one of the first aikido videos I ever bought! No clue where its at though...
The Ken Ota Aikido video series was filmed in and around Goleta and Santa Barbara, Calif.
Ota Sensei's dojo is still there at:
Goleta Aikido with Ki
Goleta, California 93117
And his senior students still teach classes there, see: http://goletaaikido.net/video.html
Goleta is a suburb of Santa Barbara, Calif - a pleasant little town and of course, beautiful along with Santa Barbara, which is 120 miles north and west of Los Angeles, Calif, driving along US Highway 101.
Ota Sensei is 92 and still with us (along with his wife Miye, who is 94). She deserves a ton of credit, having supported and worked right alongside Ota Sensei all these years to make the Goleta Aikido Dojo a continuing reality and a Santa Barbara institution: http://en.wikipedia.org/wiki/Ken_and_Miye_Ota
I hope that helps, and I suspect there's many of us here on AikiWeb who have seen Ota's Aikido videos, which were made 30 years ago, way back in 1983 or so. How time flies. :-)