Fascinating video.
In answer to LittleStar's video I would speculate that yes, more than 2pc of soldiers swung their sword to kill. You've got to remember the 2pc stat is for a few specific wars and that, as the video says, modern armies do a huge deal better. You read Generation Kill, the lieutenant states to the journalist that each and every one of his men will shoot back. They have no problem with killing. I believe him. Volunteer armies that undergo intense training are a greatly different beast to conscript armies that don't - and I wish the issue of volunteer vs conscript had arisen in that video.
But anyway. Training is the key here. He put the key to overcoming that down to getting used to attacking humans and engaging in painful realistic practice against other humans. And I don't see how you learn the sword, or any other close in weapon, any other way. Certainly all of the martial arts I've done, a huge amount of it is sparring against other people and it hurts. Get them before they get you is something you learn quick. And as such, I don't see how you'd get only 2pc of medieval soldiers willing to kill someone face to face.
I would also speculate that starting younger and a more wide spread culture of hunting could also result in medieval soldiers being more willing to kill.
That said - notoriously, it was a shock for the aristocracy to die in battle. Partially that's because of how well armoured they were, and partially that's because they were worth more alive, and partially because often they'd be fighting kindred... but still, you can see that killing was still something of a taboo.
As for the whole love & family thing - you talk to anyone who was in the military and man, its tight. I only did two years in the OTC and have seen barely anyone from those days since but even in that lowly branch of the military, you form tight, tight emotional bonds. Imagine how tight the bonds are between those who lived together permanently and underwent such great trials together. The army really does try to make everyone your family and to take up that responsibility for each other.