During a recent install of 4.7.1 I got to the stage where I was about to start adding content and thought I grab a quick look at some of the videos. So I opened the front end in a new tab (which because I had not yet added any content displayed the /config/splashes/noNodes.aspx page) and clicked the link to:

• Document types A walkthrough of how to create document types, add properties to them, and why document types are ..

The above is a straight cut-and-paste and providing the link is saved with this message, you will see that the URL the link above is trying to go to is:
http://umbraco.orghttp//umbraco.com/help-and-support/video-tutorials/introduction-to-umbraco/sitebuilder-introduction/document-types.aspx?ref=fromInstaller

http://umbraco.orghttp//umbraco.com/????
All the other links are the same. Has something gone amiss on the AJAX?