It is my impression that Lynda.com have designed the contents of their instructional videos, determined what each chapter should contain and filmed them as distinct chapters.
Kelby, on the other hand, do not seem to have designed the content but merely filmed a dialogue and cut it into pieces in post production. The effect of this seems to make the videos somewhat disjointed. Their presentation is also often terminated in mid sentence.
I also found it frustrating that the Kelby studio videos were subject to background noises; everything from people laughing in the background to what sounds like people making coffee. Distracting.
The Lynda site is also much better to search/filter for those videos in which one is interested.
So, Lynda.com by a mile.