Over the last several years, something I have tried to do is cross reference the content of Tae Kyon, since many people say it led to Tae Kwon Do, while just as many people say it didn't.
What I have is consistant proof through video footage and written text that Tae Kyon gave Tae Kwon Do many of the kicking techniques it now uses.
Why do I make that statement?
1. Consistant footage on Youtube (a great resource btw) that shows Taekyon fighters doing the same kicking attacks (many of the same kicking anyway) modern TKD uses. These include: roundhouse, stepping attacks, spinning kicks, jumping kicks, and jump spinning kicks.
2. The footage from Human Weapon that shows Jason and Bill doing leg techniques that agree with the footage I have seen previously.
3. Written text that corroborates the above.
4. The way we did techniques in my organization that seemed to directly reflect this influence.
That's pretty circular proof... Your "consistent YouTube footage" could all be from one person or from people who learned in your organization, or even simply mislabeled. The Human Weapon footage is really nothing but more of the same. Your written texts would need to be cited -- and I'd argue that they aren't really much evidence unless they're in Korean, or otherwise document historic Taekyon in context.
Suggesting that the techniques are similar isn't much support, either. I could equally well argue that Mauy Thai or Savate influenced TKD, because either style also has some of those same techniques.
I don't have a dog in this fight; TKD is not my style. I do suspect that indigenous Korean fighting approaches influenced the well-document Shotokan basis of Tae Kwon Do. While I'm sure many indigenous systems were suppressed -- I'm equally certain that many were more quietly preserved. A friend of mine learned a style of Tae Kwon Do that had little resemblance to modern TKD when his father was stationed in Korea; the best he knows is that it was a family system, taught to him by a neighbor who didn't belong to any of the existing TKD federations/organizations.