How is this accomplished?

Why are people so afraid of him?

Probably because he's hiding behind stuff, sneaking up on them and yelling "aaaah"?

Rrrrright... But once the element of surprise has set in and they've had a moment to evaluate the situation, why would they still be so freaked out?

Because they're the guys friends, and scripted reactions are better for publicity than actual reactions.

My body is over the ocean!!!

Because you humans are not entirely rational.

Little people.

Small hands.

Smell like cabbage.

I'm trying to figure out the gimmick. If it's happening live, then he has some amazing props and is clever. Off the top of my head though, scripted reaction and he's doing some visual effects with some body parts wrapped in green. But, I just can't figure out the exact mechanics of it.

*timeshift

Adding video to channels (Timeshift) - requested by brycewi19.

To me, I can see that his actual legs are in the pants. He probably has some physical anomaly of normal length torso with shorter legs. It seems to me he is leaning the right - probably has a seat built into the "pants" on a frame so he can sit while leaning. Also, his upper body is disguised by his shirt in a frame, so you can't see the lean. I think.

Way cool illusion.

Notice you never see behind him. I think it's purely a costume wrapped around a man who's bent over forwards and crouching. Grab onto the leg prop and you can lean out to the right and it appears from one angle at least that you have two separate bodies.

He could have been cleverer with the patter. Just play it normally and see he can get people to react without freaking out. When he starts "arghggh-ing" all the time he's priming them to scream and run off.

Ahh, I think you guys are right. I was rewatching it. At 1:45 you can see a flare in his pant legs, which could indicate he's either leaned back or reclining in something. I suppose something like a sitting sling, something to catch him as he leans back. The shoulders and chest don't look right, which means he may have room to settle back.

Good spotting guys, I wouldn't have been looking for it, if it was for you.