Have you noticed the make-up video trends teaching you how to apply cosmetics to enhance your appearance?
I am not sure about that. But I can see how that might be a trend.
You can search You-Tube and they have so many user-generated videos with amateur make-up artists sharing cosmetic application techniques.
What are the more popular ones?
I don't know too many.  However, I've seen Jaclyn Hill and Manny Mua.
What technique did they use?
There's too many techniques to name I'm sure.  I don't wear cosmetics but I've come across many videos.
I do not wear them either but sometimes videos like that capture my attention.