SpeedTree artist Sonia Piasecki gives you a quick overview of how to export a SpeedTree asset from SpeedTree 8 for UE4 to Unreal Engine 4.
Note: SpeedTree v8 will only work with UE4 version 4.19.
SpeedTree documentation: http://docs8.speedtree.com/modeler/doku.php
More info at www.speedtree.com/ue4