If you click from here:
https://wiki.unrealengine.com/Videos
to here:
https://wiki.unrealengine.com/Videos/Player?series=PLZlv_N0_O1gb5xvsc7VM7pfoRAKLuIcFi
The most recent source is 4.4
But on this page the source goes to 4.72
https://wiki.unrealengine.com/Introduction_to_UE4_Programming_-_1_-_Overview
BTW this is a very good introductory series for C++ programmers.