BK -- That jerky, stuttering thing is horrible. I've never learned enough about film vs. video and frame rates to understand it, but I think that's what it relates to. (I mean, I know about film vs. video rates, but it's how the transfers and compromises are executed that matters.)
The instances where I commonly experience it are on commercial Blu-rays in which the studio has transferred, say, an older feature such as a documentary or interview which played beautifully on DVD, and it now plays jerkily on the BD. Fox movie releases such as Cleopatra come to mind. Those wonderful long "making of's" play fine until they show a clip from the film, and then it's Jerk City...but watch the same feature on the older DVD and all is well. It's something in the transfer of certain things from one format to another.