WARNING: [youtube] Falling back to generic n function search
         player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js
WARNING: [youtube] I-mVtdAqeJM: nsig extraction failed: Some formats may be missing
         n = GSf_EhB1g1VrDtyYq ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js
WARNING: [youtube] Falling back to generic n function search
         player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js
WARNING: [youtube] I-mVtdAqeJM: nsig extraction failed: Some formats may be missing
         n = m4Mlq4nRNPwKBK5Ym ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js