The slider is on the left so that you can easily grab it on the edge of the screen without having to worry to hit other buttons. What's wrong with it being on the left?
Maybe I'm going to make this configurable. Actually the touchscreen of the N8x0 isn't sensitive enough to make single taps work well. To often you end up opening stuff instead of scrolling. The N900 version defaults to single tapping because its touchscreen is excellent.
Can you get YouTube to play on the N8x0 with any app, or maybe the problem lies elsewhere?