well, in the code as downloaded the <img> tag looks like
<img src='{$poster}' width="100" height="100">
changing it to:
<img src='{$poster.url}' width="100" height="100">
did the trick, sure you replaced the correct $poster variable?
Interesting plugin,
Just checked it out and got it working instantly.
Can you tell me the filename of the file you have pasted the code in and show me the code so I can check what you did wrong?
(propbably the code from Header.php)
And what is the swaprate of your images in the plugin options? Have you added more then 1 image?
Nevermind this one, I got the answer I think
I set the before and after tag, as this is default