Cute.
Pretty decent punchline, and the best part is you didn't ruin it by dragging it out. There obviously were some issues.
The flash file looks very compressed. Did you export it as a .swf file? I noticed at the end it says "Subscribe", so was this originally made for YouTube? For the sake of quality it might have been easier recreating the whole thing.
You did well with the facial expressions and body language of the character. It met with your voice acting quite well and the whole casual approach your character had to the end of the world.
The character looked very simple, but hey, it was a short skit, who cares? Could have done a little more on the background imaging at the start. Also, the thickness of the lines on the rock/table were a little much. They almost ate up the screen a bit.
At the end of your animation if you include the following script it will stop sounds and the looping issue you have:
stop();
stopallsounds();
Anyway, good joke let down a little by the animation.