Ambigram_Rotation_by_Insanity_Prevails.scmI saw this script in gimp2.7 and it didn't work, so I copied it and put it into gimp2.6.11. It requires two layers to work. I ran the script with a heart image. When I wanted to run Playback to view the animation, Playback wouldn't run.
Playback works fine for my other animations.
I did a Google search and found the script. I deleted the one I put in my scripts folder and downloaded the one in DeviantArt; it has the same problem with Playback. I ran the script using the default settings.
The script leaves many different-sized layer boundaries that need to be set to image size but doing that still does not allow Playback to run.
I saved it as an animation (gif format). Closed it, then opened it. Still the same problem. I went to Filters > Animation and noticed that most of the scripts in there were grayed out, but Settings was available but not Settings with Semi-Flatten. I changed the default speed (30ms) to 100ms and then it would play back.
For me, the script left the image in a sorry state.
I'm attaching the xcf file of the animation. It too refuses to play in Playback. Perhaps you could try it and see if it plays for you.