So... a little help with Halo 4 green screen?

I have chroma keyed in the past, but my video results look terrible. The RGB values for the blue HUD get distorted and they go all purple. Was wondering if it was maybe my game capture card, but I’m not sure. You can find my video here. Yes I know the BR is partially see through, I didn’t assign the threshold values very well, I know how to fix that.

Would love some help!