Unbelievable,
I've been searching this same gremlin for a year now.
At first, the only time my brake lights would come on, is when shifting at high rpm.
As time wore on, the problem got a lot worse.
My car has a Centerforce Dual Friction clutch, so I guess the extra clutch pedal effort is flexing the plastic pedal box more than normal.
I was surprised to see how much that plastic crap flexes when depressing the clutch pedal.
However, I bent the metal tang that contacts the brake switch, and now my brake light problem is gone.
However, now I worry about that plastic pedal box cracking & breaking sometime down the road.
I hope this link works, this video was shot by a buddy to show me what my car was doing (and yes, I was sooo lucky for him to catch the run where I missed 2-3 shift...however, the clutch was down a long time while I tried to find a gear and this shows the brake light issue better).

 

Since this thread is almost 3 years old, you weren't searching correctly. But i DO hope it helped you with your issue.

 

You are correct, I wasn't using the correct search terms, and, being an old fart, I just don't spend much time on the computer.
However, I am so glad this old thread did help me!!

 

Why waste money when all u gotta do is bend a tab?