I used a comb filter and adaptive line enhancer (ALE) to eliminate the harmonic tone and white background noise in this recording (https://youtu.be/PB_8iOCm92c).
mbt_70_experimental_us_army_1970_360p.mp4
COMB_output_fo=134.8_bw =.97_best.mp4
y(n)_ALE_output_M=64_mu=0.000010_L=3.m4a ( for download issues try y(n)_ALE_output_M=64_mu=0.000010_L=3.mp4)