meh...
the idea was good and original but performed pretty bad. The yoshi was drawn poorly, you didn't draw the red spikes on it's head and neck, the shell on his back and his shoes. You could have drawn those even if you were new with flash.
And I really don't get it why you recorded a part of the game.
And you might wanna practice a bit more before submitting your stuff here on newgrounds.
But don't let me discourage you. your ideas are really good, only thing left is the skill so you're half way there.