MANCHESTER’S One Love benefit gig could become the most-watched to date — with more viewers than Live Aid.So far, at least 43 countries are on board to broadcast it live, with America’s ABC signing up on Friday.Networks in China, Australia, South America and across Asia will also air the gig live and in full, with many more in talks.The event will also be streamed online, meaning the total number of viewers around the world could surpass the estimated one billion who saw 1985’s Live Aid concert.And it will eclipse the 600million who saw Nelson Mandela’s 70th birthday tribute concert in 1988.A concert source said: “This is without a doubt the biggest event of its kind in recent memory, and with so many major broadcasters now on board around the world the potential for it to have a major impact globally is huge.“Obviously the list of stars involved is incredible, and without a doubt it will be a huge TV draw in the UK but with people like Ariana Grande, Coldplay, Justin Bieber and Katy Perry involved the global appeal is enormous.“It could well be broadcast in close to 100 territories in the end, and the online stream means it could…