I have viewed his video before, that being said, there's no way the wheel can come off, if you noticed that the outer CV joint couldn't possibly pass through the knuckle and bearing carrier/housing, the outer CV joint with the splined shaft being attached to the hub by the nut and attatched to the wheel is much bigger than the opening in the knuckle and bearing carrier preventing the wheel from detaching from the vehicle unless the CV joint and spline shaft breaks apart, which is highly unlikely.
That being said, I wouldn't drive it...unless it was an emergency and I feel it wouldn't end badly even if the bearing failed drastically, which I doubt would happen from just driving it for short runs, if you drove it for an extend time the bearing could heat up and then fail completely.
Concerning the video, Eric is an experienced and capable mechanic...but he failed BIG time in his video in his attempt to remove the hub from the bearing and reassembling it, this process should be done with the assembly off the vehicle and using a 20 ton hydraulic press, also notice with all his hammering a beating on the bearing that the bearing never came apart, this just shows you how strong the bearing is even being worn out which should give you a little peace of mind if you do have to drive the 4Runner on a short run.
While I criticized Eric's method of removing the bearing, I will give him alot of credit for leaving this video on YouTube, he has never replaced this type of bearing before and without having a press he did the best he could, I know he realizes his mistake and admits it in the video and that other knowledgeable people would see it and his leaving the video on there shows he admiting his mistakes in video.
You shouldn't have to worry about this though if you're getting a complete bearing/carrier/hub assembly from the forum member/s who sells them, it a easy job when you don't have to separate and reassemble these parts.