Well, AME 3 is only if you have a 4.0 board and it had some problems. The changes they made to vB 4 kind of messed with The Geek's ability to make it work.
Since your on 2.5 you can try what I've got. I presume the Replacment Code for the paid version is the same as the Lite Version?
Code:
<imdb><script type="text/javascript">ajaxinclude("imdb.php?mid={param}")</script></imdb>
If it's the same, then you don't need to change anything.
If the paid version has different Replacement Code, then just go into the Replacement HTML in the definition, paste in the code that's needed and change:
to:
. Then you should be all set.