What you are leading yourself to believe does not seem to be important or factual. It does not even seem to be logical. Do you think that the folks who watch the video are going to come post, "I am glad that was in video format, I liked it!" Surely you do not believe that... We, as a group, do not post about what we like - we post about what we dislike. If you see a few posts complaining then you can reasonably guess that far more do not mind.
Or alternatively -- and just as reasonable a guess -- only the people who have an extreme dislike for the videos post complaining about them, and the far more who do not post on the subject just don't feel strongly enough about it to complain. I fall into that category; I haven't complained about the video, but I think that a video interview is an extremely poor medium for conveying information.
People come to Slashdot for the comment section. Presumably, if there actually existed a large number (thousands) of people that like these videos, then they would respond to some of the negative comments. That rarely happens.
The complainers have had a positive effect, by the way. Originally there were rarely transcripts of the videos, which made them useless to anyone who has better things to do with their lives than watch them. I doubt we would have ended up getting transcripts for most videos if it wasn't for the complaints.