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] umPGmt3vUCU: nsig extraction failed: Some formats may be missing
         n = zwAZX4Exv96AVALDY ; 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] umPGmt3vUCU: nsig extraction failed: Some formats may be missing
         n = l8cifLQuupi_6cf00 ; player = https://www.youtube.com/s/player/e7567ecf/player_ias.vflset/en_US/base.js