The whole quote:
A third major challenge concerns clearance of photo rights. This became evident when we began to request image files from other museums in order to show them side by side with our own works within the new Art Stories universe. The costs were tremendously high. Just one image could cost several hundred dollars, and even that would only buy us clearance for a limited period of time. The labor involved in writing to each rights holder, asking for files, describing the intended usage, and so on, turned out to be a major drain on our manpower. What is more, the use of images from other collections prevents us from posting Art Stories videos on YouTube, where they could gain much wider exposure than when shut in and restricted to the museum'ss own website..