Using the Search function on the PBS website (PBS.org) or browsing the Archive section of shows are the two main ways of searching the PBS video archive. Although the search function is not limited to video, this can be easily circumvented by accessing it from the PBS video website.
Most shows on PBS have archive sections that can be searched individually for previously broadcast material. "NewsHour," "Frontline" and "Nova" are three of the longest running shows with the largest archives of video material as of 2015. Besides searching for full episodes, these shows also offer thousands of short clips and fragments that can be explored using the search function of the PBS website.