If I might add to this. What Protomech is talking about can be seen if you watch a motorcycle race in the dry vs the rain. In the rain they don't lean over as far, so they tend to hang off further. Actually motorcycle racing for 10 years ago would be a better example. The tires and bikes are so good now they're dragging knees in the rain. But I digress.
I also suspect the Empulse is designed to be ridden by normal Americans, not Leprechauns who weigh half what most of us do. So, the bike might be a bit more reluctant to turn in, being a street bike the steering would definitely be heavier (read: more stable), and he is trying to look good for the camera.
I have seen Steve-O race the RR in person, and he can rail a corner, but he doesn't look like that on the track. I found it odd too. Also, the bike doesn't look like it fits him very well, as in the reach is too far. It doesn't look like a proper position at all. This also might explain the exaggerated style.
You see me right at the 4:00 mark pointing out differences between the models
Ahem. Pig
On a side note: Can someone explain the purpose of hanging off the bike when it's going through a curve (4m27s)? I presume that this is done to avoid tipping the bike too much, but would tipping too much cause the body to hit the ground, or would it cause the wheels to grip less, or something else?
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It's about keeping the bike as upright as possible (making the contact patch of the tires larger?) to keep it from low-siding (sliding out from underneath you).
Another way to think of it is the tire has a certain maximum lean angle (deviation from straight up = 0 degrees). On street tires this is around 45 degrees, on race tires it can approach 60 degrees (rough numbers). As Brammofan says, if you exceed this maximum lean angle then you will low-side the bike.
You can take a corner at a higher speed the farther your center of mass is inside the turn.
Therefore, if you're at the tire's maximum lean angle (with a reasonable safety boundary), you can increase your corner speed by moving your center of mass inwards .. eg leaning off of the bike into the turn.