"Note - Ambient Occlusion map must be exported separately, this is just for presentation purposes" 7:46
What should we need the separately exported AO for? And how and for what programmes?
Can I just use the AO baked in Blender for the Unreal?
As far as I know, the ambient occlusion map is its own thing and has always been baked separately. It'll help you tone the occlusion just the way you want it, you have more control with AO being its own map. If you have maps mushed together, you have a hard time dialing things and fine tuning things.