Seems like 100%. Are the mobs maybe just alot lower level than he is?
This was before the nerf to Aggressor and Crit Rate occured, which happened after the initial week of kCBT3.
In that video, they’re using the Barbarian skill ‘Aggressor’ to skyrocket their high critical rate. It’s even more apparent as they have points only in STR and not DEX. 
(Current stat effects; STR = Raises Crit Damage, DEX = Raises Crit Rate).
This has been changed since then, it requires a lot more DEX and a lot more levels in Aggressor to come anywhere close to that. Aggressor doesn’t increase Crit Rate by that much any more either.
The weapon being used is this, it doesn’t add Crit Rate or DEX either.
Ah gotcha, thanks. Forgot to check the patch notes. Gonna do that now.