"the rest of his shots are at half draw making it difficult for them to do any serious damage to an armored combatant"
Agreed as far as his strength goes, the reason being that real armour have "DR" and not just "AC". But if you look at historical source half-draw WAS used in battle (Bayeux tapestry and many other depictions as well as texts) for when the enemy got closer. This is of course with a stronger bow if you want to pierce armour.
"and very likely wounding instead of killing an unarmored foe"
Any arrow, regardless of strength of the bow, will primarily wound, unless you hit a vital (artery or hearth/lung/brain)), a strong bow will "just" penetrate an unarmoured foe completely.
"1) Knocking the arrow on the right, and having the arrows strapped to the thigh, and taken in multiples by the hand.
Nothing new here, these techniques are still used and taught, especially among the Eastern."
You would be surprised at how many historians/archers claiming the opposite. Especially for Medieval European archery, and they claim the illustrations he uses is made for "easier depictions in books not needing to "break" the line that is the bowstring", and that you would loose all accuracy doing it the right side shooting, he shows that it can be done accurately.
"Technically the video did not mention that he could catch an arrow midair, merely that he could retrieve and fire back enemy arrows. If you notice, there is a metalic screen behind him, which stops the arrow's momentum before he grabs it. Useful skill when the enemy is firing a lot of arrows at half-draw, but this will not work at retrieving arrows that are well embedded in a surface."
Wrong! Look around 3.05 in the film and onwards: first he does it standing still, then while jumping and spinning, shooting the arrow before hitting the ground! True the arrow fired at him is probably not shot with the strongest bow.
"3) Repelling arrows. Half-draw against half-draw. Typically the battle would be filled with arrows, so there wouldn't need to be all that much accuracy needed anyway. Lars would have problems if the arrows against him were fired at full draw."
I agree, it is totally useless in a battle. Most RPGs (like NWN) are depicting skirmish fighting, rather than battlefields. You might still consider the usefulness, rather than just ducking/moving away. But as a NWN feat it should be represented.
I agree some sneak attack would be added, note that he fast shoots two "skulls" in the eye from some distance (6-8m at least).