Don't know much about her or this series, other than it aired on PBS and I saw this in the mid 70's when at that time most PBS stations would show adult programming in mid-day.
These episodes that I've seen so far are 1969-1970, don't know when it exactly when it was produced, can't seem to find anything up and down the internet, all of these seem to have been uploaded by Ms. Lettvin herself. Also I don't know how old she may look to everyone here but her YT profile says age 85, which means she was 42-43 when these were made. Certainly looks younger than most women would of in that time.
Also this particular episode I put up which was shot outdoors, must have been harder to do that it would by today's standards because from what I understand there was no such thing as hand held video equipment and I'm sure PBS stations were behind commerical TV when it came to these things.