If you are a BT customer and are having trouble accessing the "Files" page (because BT are blocking it) here is a workaround:
1. Log in to MyBt
2. Select "My Security"
3. Disable "Web Protect".
You will then be able to access the files page without issue.
I strongly recommend you follow the same steps to re-enable if after you have installed forge.
4. Contact BT and demand they remove this site from the blacklist. Advise them that, not only is this site VERY safe, but by blocking it they are encouraging people to download unsafe copies of forge from suspect sites!