From medieval fighting training, I can tell you right now that their shield technique would get every one of the soldiers killed in actual combat. That is NOT how to use and carry a shield, unless you just want to be beaten to a pulp with it.

For starters, the stance is all wrong. The person carrying the front shield is completely relying on the soldier behind him (see the knee) for balance. Secondly, the shield soldier is prepared for a straight on, pushing attack at chest level. That's not reality. If it were ME attacking, I would push on the left side of the shield to tilt it, then push off-angle to tip the soldier over that balancing knee.

Basically, they should train with people that know how to carry and use shields. :>) If I ever came across that on a battlefield, I don't care how big the opponent is, they would end up on the ground with me stepping on top of their shield.

Also, if the attacker has any weapons... they won't fight through the shield. The guy standing next to the shield man is wide open for any sort of attack. Look at how his head, shoulders and right arm is exposed.

Either train in how to properly carry a shield or else don't rely on one. If you can't use it properly, then it's just a liability. Only use weapons that you KNOW how to use. (Yes... a shield is a WEAPON, not just a defense. If you don't even know that much... then consider learning first).