I was unable to get past the You Tube account verification on my phone, when I tried to enable that functionality. Tried probably 10+ times, and every time it told me the phone number was not valid. Tried my home number and got the same message. My wife's (identical phone, on the same carrier) worked on the first attempt. Go figure. After trying to verify my account a couple more times on mine, unsuccessfully, I tried it on my desktop machine and worked immediately - using the same number that it had previously insisted was invalid.
After that the Live Broadcast worked perfectly.