The animated battler sheet from the HF packs are using the same format as Holder.
PVGames wrote somewhere that his demo videos were made with Symphony and the Holder-addon to symphony.
I know that there are a few other scripts that use Holder's format, you might search for that to find alternatives.
That said, depending on what you call simple you will probably have no success, because each of the battlescripts needs some additional complexity to handle animations.
If you do not wish for specific effects, I believe Battle Engine Symphony is one of the easiest out there - because it has defaults to anything, you basically only need to put in the scripts and then give the correct notetags to all enemies to have them use the correct battlersheets.
However, Symphony can become very complex if you try to modify it's action sequences - since everything is configurable there, it can become quite a task to configure everything if you do not want it's default.
However, all alternatives might reduce the possible script complexity only by removing additional options (thatyou don't need to change in symphony) - but they can't get below that minimum of setting up the scripts and giving each enemy it's own notetag data to determine the animation. That is because the animation can't be loaded into the enemy by default.
If you have a problem with a specific script for animated battlers, then post a link to it and give the specific error or problem you have after trying to configure the animations.