youtube.com problem (also with videos.google.com)

Another issue with the previous iRules is when the link for youtube is down. There will be no redundancy.

I think you can create a new pool with priority enabled, so the LC would be able to re-select the other link when the link for youtube is down.

  
  when CLIENT_ACCEPTED {      
      if { [matchclass [IP::local_addr] equals $::youtube] } {      
      pool   
      } else {      
      pool       
      }      
      }