I took it upon myself to take this original footage:

and remaster it.

The original is distorted, too dark, monaural, and has many other defects.  The hardest to get rid of was an annoying high pitched whine/tone which pervaded the entire piece.

Here is a sample of the original noise on the track:

I analyzed the frequency spectrum of the noise:

There are several loud peaks in the file but through trial and error I was able to isolate 5236Hz as the offending frequency.

Here is pure 5236Hz.   See if you can hear it in the original noise recording above:

If you wanted to find this note on a piano, you’d need a very special piano with an extra octave at the top end.  The “E”(mi) note in that extra octave would be the offending tone.

I applied a “Notch Filter”:

(The Q value is somewhat technical, but intuitively the higher the value, the less dampening of frequencies around 5236Hz.  More details can be found here: http://www.learningaboutelectronics.com/Articles/Quality-factor-calculator.php which even has an online calculator for ‘Q’.  Generally I use a Q of around 4, just speaking from experience.)

After applying the fiter, we get this spectrum:

Observe how a narrow band of frequencies around 5236Hz has been removed.

This is the same sample of noise with the whine/tone removed:

That was how I removed that annoying frequency from the entire track.  After numerous other adjustments, the result: