I was using Chromium Browser on Linux, to see World Cup 2014 videos on YouTube. Some videos were not available in my region because of restrictions by region. If you are also seeng the same message, the you may want to setup a SOCKS proxy, and use that to bypass the YouTube restriction. For this to work, you need an SSH server what is located in some region from where you can access such videos.
Setup Socks v5 proxy:
ssh -CND 1080 user@some-ssh-server.example.net
Start Chromium browser with this proxy by default:
$ chromium-browser --proxy-server="socks5://localhost:1080" --host-resolver-rules="MAP * 0.0.0.0 , EXCLUDE localhost"
ATTENTION: default value of option force_s3tc_enable overridden by environment.
Now you can watch those restricted by region videos.
Enjoy!