How to recreate tutorial https://www.youtube.com/watch?v=-sJsR0y7R8U in Blender.
*Selecting Multiple edges is by holding down shift key.
[ 2:03] Open Blender (and install script :P)
[ 7:43] Uv Unwrap
[10:41] Lightmap Unwrap (how to create second UV)
[16:14] Lightmap Unwrap (proper)
[23:50] Unreal Engine
[25:50] Fixing Blender export settings
[26:50] Setting up two walls in UE4
[29:35] Building Lights – start
[31:10] Building Lights – End
[33:40] Building Lights (Production) – Start
[38:15] Building Lights (Production) – End
[38:40] Lowering Engine Scalability settings
[40:26] Making adjustments to Lightmap in Blender (setting buffers to 4 pixels)
[41:40] Reimporting BlenderWall and building production lights again
[46:06] Building Lights (Production) – End (better lights in low engine scalability)
Source