In the Grid component with infinite scrolling, when a user scrolls down, the grid will bounce them back up to the first row when loading the next couple of rows. We get this same behavior in our application so it doesn't seem to be a mistake in the demo. We've encountered this issue in both version 1.x and the most recent version of Kendo.
Since this is also broken in the docs, I don't think it's necessary to add screenshots or code.