In a nutshell, the animation manager works like a hierarchy. More important animations will play over lesser important ones.
The manager has a list where 0 being the most important and the higher the number, the lesser and so on.
Under the [CUSTOM] palette you'll see a section for animation manager. From my understanding, the PLAY ONCE block plays an animation once and returns to the previous animation. As for the looping blocks, it uses the hierarchy.
For example you could have a category hierarchy like this:
0 : Attack
1 : Jump
2 : Duck
3 : Run
4 : Walk
Syntax:
<Loop [ANIMATION NAME] for [TARGET] using [CATEGORY]>
Example:
<Loop [Somersault] for [Self] using [Jump]>
To stop the animation, use the <Clear Current Animation for [SELF]> block or any clear block that fits your scripting. It will stop and go to the next animation on the hierarchy.
The default animations chosen on the manager UI under the category list will play if no animations apply with the categories. These would be your "IDLE" animations.
Hope this helps, and I hope I have the facts right. If anyone else wants to chime in, be my guest. I just learned to use it myself. Great for complicated boss battles.