Is my sample just poor? I picked a random math video and the first problem is demonstrated wrong. Y = 0, not Y = 10 verbally, the writing on the board is correc

Is my sample just poor? I picked a random math video and the first problem is demonstrated wrong. Y = 0, not Y = 10 verbally, the writing on the board is correct but he glosses over it very quickly not catching he said anything wrong (error around 2:00). http://www.youtube.com/watch?v=woqq3Sls1d8&feature=youtube_gdata http://www.youtube.com/watch?v=woqq3Sls1d8&feature=youtu... [Update 1] Watched through to the end and he makes more errors and they caught other errors and put in red bubbles to note them. I appreciate the effort and idea behind the project -- hopefully we can actually get experts to provide quality course materials. [Update 2] Odd, watched more of the math videos and he seems to do a better job on more complicated material -- it could be he's too much of an expert and not patient enough to teach the easier material or just assumes it is easy and even with a few errors people will "figure it out".