Yeah... Actually, I figured this out shortly after posting the video and manual on this thread. But couldn't post anything on it cuz the forum went down last night. I couldn't get to it anyway. ( I had a video to post and everything. I will paste the link below.)
Since the headlight button is on the throttle control (Which is lit up and therefore powered.) I assumed the wires coming from the switch already had a 5-Volt charge coming from them. Not the case. They were dead. I needed to use the 5-volt feed from the controller and add the wires from the switch into the loop. (As an interrupt.) (I used the diode testing mode on my multi-meter, and found the switch's circuit right away.)
So... To make a long story short. Here is my situation. The power isn't clean. It must spike when I hit the throttle. My light works like a charm, until I hit the throttle. Then it goes out.
The controller that they have integrated into the Magic Pie II is pretty damn crumby. By spring, I'm going to need an external controller. I have driven this motor for roughly 100 miles so far. (I have a computer on the bars.) This thing has shut down due to heat 3 times in that 100 miles. And it's freakin' November in Cincinnati. lol!
Oh... Here is that video of the light working.
PS - I mistakenly ran 53 volts through one of my two lights. (I had planned to put two on the bike.)
The flashlight didn't make it!