Not bad for the second try!
For a second flash, this is pretty good. Sound effects were used in places quite well, but lacked an overall theme to match the environment.
Stick movies are very hard to stand out from the crowd since there are many others, and as such those that do stand out are exceptional. Compared to the others, you will probably know yourself it doesn't stand out.
However, that's not to detract from your efforts. You did something you wanted to do, worked at it and got a finished product, so be proud.
I've never tried flash and therefore don't know what difficulties there are. However, the animation was fairly smooth. Transitions between the "hero" were useful, as so many movies use the same main character throughout the sequence. Adding a pinch of humour at the end left the flash on a high note, good choice. The stage destruction was fine as well.
Tips for improvement -
.. Add some detail to the backgrounds - keeps the viewer's attention
.. Have a stab at introducing a music theme in your next submission
.. Make something other than a stick movie ;)
.. Try to come up with new ways to perform actions
And above all, enjoy it while you learn. Best way to progress is to have fun while you do it!