YouTube videos are muted by default in Google Chrome browser; this is a known issue affecting all users and not an issue on this site or with your computers. Some users are reporting problems also with Firefox and Opera but the admin of the site here tested Firefox, Opera, IE and found the problem exist only in Chrome so Google who own Chrome and YouTube is looking into this issue it seems to have started around the 3rd of October.
Thanks mate I use Chrome and it is happening to me I thought something was gone wrong with my sound card or something. Google owns YT and Chrome they better get on the ball.
