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] M-yKX8SGXe0: nsig extraction failed: Some formats may be missing
         n = D-i4ZHdKKv6MSTh9N ; 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] M-yKX8SGXe0: nsig extraction failed: Some formats may be missing
         n = vNZqpFKtrVAn6oY-X ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js