Well I came up with a solution but it didn't completely fix the problem. The problem was that something was offsetting the landscape thumbnails, they didn't fit the wrapper.
Now I'm not very good with jquery, so my solution is probably not the best one. All I did was made sure the thumbnail would start aligned left inside the wrapper. So I just added
'left':0+'px', to the thumbnail section (I believe line 555) of the jquery file
// Scale each filmstrip image if necessary and position it within the image wrapper
So the thumbnails now fill the entire wrapper, but if you look closely at the thumbnails of the landscape oriented images you'll see they're still distorted. They fill the wrapper height but squish to fit into the width.
I'm still open to suggestions to better fix the problem...