Question

Can I make the AutoScroller scroll seamlessly, without the 'gap' at the end of the scroller content?

Answer

A DHTML scroller is not really scrolling. What is happening is that a layer under another layer is being moved below the upper layer's clip region. Content in the layer below that falls outside of the clip area is hidden as a result, and the appearance is as if the content was 'scrolling'. And obviously that moving layer with the actual content can only be in one place at a time.

For the AutoScroller this means that the content layer will only be repositioned at the bottom of the upper layer's clip region again when all content has moved/scrolled by. And then the upward movement can start all over again.

A seamless scrolling effect can be achieved by using more than one content layer and making them take turns in the scrolling movement. But AutoScroller is just a very simple, basic scroller and thus doesn't support that.
Scroller Genie however (= commercial extension: http://www.dmxzone.com/showDetail.asp?NewsId=4952) is far more advanced and does support seamless scrolling.