It would be extremely useful to be able to adjust the playback speed (without affecting the tone of the speakers voice -- see pluralsight). Presently, watching this stuff is expensive in terms of time and boring as heck.
It would be useful to have a time index into video content such that a lot of the fluff, otherwise essential for first time viewing with a cup of coffee and a lot of time, can be can be skipped.
While a search for the entire site is useful, a search for each particular sub area is also needed (as a separate search box on those pages). In particular, with over 50 pages, I don't know whether these suggested have already been made and responded to.