That's not really Xantar, you silly.

Although he apparently is very strong and muscled. Oh and I bet that movie is real... but: you never see more than 5 or so chin-ups. Maybe the guy does 5 of those, rests for 2 days, does a few more, etc. And he just made it look like it's all in one training.
Edit:
Xantar zegt:
manasecret believed that I would post a video of myself?
Xantar zegt:
and actually, rock climbers mostly have strong forearms, not pull up muscles.
Last week saw myself in the mirror and suddenly thought: "I don't want to get any beefier." I like the way I look now. Well, the arms and chest. I plan to work on the abs and maybe back.
So..... I quit the training.

I'll still do the exercises once in a while, to stay in shape, but I don't have to be stronger.