Martially, "internal" has some advantages over an "external" approach:
1. It allows a person to maintain an extremely stable structure that, at will, becomes hugely difficult to move or offbalance, or to take-down or throw.
2. It allows a person to strike and punch continuously without having to re-chamber the hip and create a gap that an opponent can exploit. His strikes and kicks will be extremely heavy and concussively damaging while using minimal outward movement and effort.
3. It allows a person to be extremely "sticky" and "heavy," spiralingly tight and smothering in grappling
4. It allows a person to receive/absorb and re-route the force from a "non-internal" opponent's kicks and strikes and neutralize their power... and to exploit the opponent's force to augment one's own.
5. It allows a person to move and step without compromising stability and "groundedness." This reduces vulnerability to being off-balanced by an opponent, and also allows a person to use the entire body in motion, backed up by the ground, to apply power in ate-waza.
Asking* for someone to provide a video of a competent internalist doing these amazing things to a competent externalist in an alive environment will as futile as always has been, isn't it?
*Yes, it is a rhetorical question.