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] KTPMb2YK34U: nsig extraction failed: Some formats may be missing
         n = zRPuyp6e2I6n61TCl ; 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] KTPMb2YK34U: nsig extraction failed: Some formats may be missing
         n = CUMf2APZHgY0gk6-S ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js