Some tips...
Great choice of music, but you do need to improve a bit. Yes, you already know that your lip synching is not the greatest. Good quality lip synching takes a while to do, and most of us can get fed up doing it. I suggest having 5 or 6 different mouth movements (instead of 2 or 3). It can save a lot of time if you put all your mouth movements into a movie or graphic clip, and get it to loop. Then edit it to make it fit. It also looked like the main guy (the singer) was moving really jerky. Use multiple layers and shape/motion tween to get the smooth motion. I hope you find this helpful. I see it's one of your first Newgrounds Flashes, and I know you'll improve. Happy Flashing!