Some parts of that clip is sped up probably due to some inconsistent compression, delayed frames, dropped frames etc. That's why it looks odd. Under a stable and consistent framerate it would look believable.
Those manuevers are really flashy and everything, but just to let you guys know, the radios they use have programmable macro functions ie you can link many individual manuevers into chains and have it played back at the flip of a switch. You can program it like a sequencer. You can record manuevers into the radio's memory too. This is not to say that guy is not one heck of a RC pilot, but it's not as difficult as it looks once you try it and practice. Using a RC heli simulator for PC can help save you a lot of money from destroyed rotor blades, booms, frames etc.
Also keep in mind that the hp/weight ratio in RC models are many times higher than actual scale helicopters and vehicles. So when you see it hanging in the air vertical etc., just remember how much hp it has compared to how light it is. Also all the materials is several times stronger than what is used in a real heli with respect to its scale.
