He didn't fall there...he was being funny and every now and then, he would lift his little butt up with the beat.
Later; however, if someone downloads a blooper video, you will see a real fall. I hate to say this but, while watching Mika take a fall over and over, it was pretty darn funny. He was running around the full cirlce, tripped, face-planted, got up and kept running. Poor thing.... It was funny...wouldn't be though if it was me. And, wouldn't have been funny if he hurt himself. But, we cracked up each time we watched the footage.