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] 6nXA78_ezYU: nsig extraction failed: Some formats may be missing
         n = 5LdxMRpf6ANqOXi68 ; 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] 6nXA78_ezYU: nsig extraction failed: Some formats may be missing
         n = V7XNus4IgYwZ8zKX6 ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js