For this new PBS special, the producers of Pioneers of Television have taken their interview with, and footage of, Robin Williams, compiled for an earlier installment on TV comedians, and supplemented them with fresh interviews of peers offering remembrances and appreciative remarks. Pioneers usually takes a simple and superficial approach to its chosen subjects, but even that, in this case, is worthwhile – especially since it features such now-resonant clips as Williams acting opposite Joan Rivers, another recently deceased comic, in a failed 1970s revival of Laugh-In.  Check local listings.