Corresponding video: snails.rm (479.5 kb)

First i imported my snail.png which had a snail on a transparent background.  Then i added a pattern slant effect as a child track of the MediaMixer (although the same effect would have been achieved by adding it to the snail.png track in this case). 

On the vars tab i adjusted the vertical slant slightly up and down every few seconds.  You can see the envelope on the track display.  It is the current track. 

Next i added a rotate move scale effect from the tiling effects folder and set the horizontal position to default where the effect track starts, and to a couple thousand pixels where it ends.  To set the number for a variable specifically, press the icon to the right of the next key frame icon, the one with the hammer and the plunger.  You'll get the variables properties tab above.