Bing.com animated main screen question.

Bing.com brings you to the main web page (are they still called portals, or is that too 1990s?), which features an interesting image that changes daily (often an landscape, sometimes insects or animals, etc), with clickable area that bring up various tidbits and clues of info about the image (the I icon in the lower right describes the item directly). Lately (or at least I noticed this lately) they feature some animation - the first time I notices this was a landscape with some trees moving with the wind.
OK, the image for Oct 19, 2012 was of Point Atkinson Lighthouse in British Columbia, with animated waves washing against the shore. But, looking around the rest of the image, you see the trees do not move or rustle, and the clouds do not move, even though I think it is a 6 second loop.
Is Bing (or whoever created the image) just overlaying a layer of animation over the lower portion of the image (the bay) - if so, why bother, why not include the entire animated image over the 6 seconds or so it loops? To me, it’s a bit glaring.
(Note, you can see previous day’s Bing images via the < icon in the lower right of the screen, as today’s image is Marshes in Cape May, NJ)

Pretty smooth loop on the water.

It seems to me there is some slight movement in parts of thee trees (second tree from the lighthouse seems to have a branch bouncing a bit up near the top), but if it isn’t windy and with the amount of compression artifacts in the image it doesn’t strike me as unacceptably still to be video.

But I’m no expert and am probably easily fooled.

Smooth looping is pretty hard to pull off, without it looking like you’re fast forwarding and rewinding the video. It may be easier to only do it on one part.