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] S6F_3ZfkydE: nsig extraction failed: Some formats may be missing
         n = leqd0-kGip7B2jP7L ; 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] S6F_3ZfkydE: nsig extraction failed: Some formats may be missing
         n = qgc2F_Ipl6xnnFeEY ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js