See the Unreal 4 engine in action in this trailer for Primal Carnage Genesis.
Creating Art with MODO and Unreal Engine
Take a quick look at how to integrate Modo and Mari into an Unreal Engine 4 workflow.
Unreal + SpeedTree
Unreal Engine and SpeedTree allow for these beautiful outdoors shots to run in realtime.
Unreal Engine - Showcase
This compilation video shows off some of the games built wih Unreal Engine technology.