What do you mean by "looping"? It looks like the KML file is
continually updated, so I'm guessing you want the map to keep
refreshing the KML layer to keep the visuals constantly moving.
You can use a Network Link in a KML file that has a refresh interval
set. I tried this, and it seemed to work pretty well:
<?xml version="1.0" encoding="UTF-8"?>
<NetworkLink>
<visibility>0</visibility>
<open>0</open>
<refreshVisibility>0</refreshVisibility>
<flyToView>0</flyToView>
<Link>
<href>
http://www.srh.noaa.gov/ridge/kml/animation/N0R/
SGF_N0R_loop.kml</href>
<refreshMode>onInterval</refreshMode>
<refreshInterval>2</refreshInterval>
</Link>
</NetworkLink>
The <refreshInterval>2</refreshInterval> part means that ever 2
seconds, it will refresh the overlay.
To learn more about Network Links, check here:
http://code.google.com/apis/kml/documentation/kml_tut.html#network_links