Two green and one blue prongs (rockers) are connected by pink double bar (conrod) to create a 4-bar linkage.
They are also connected by two spring — bar assemblies, the purpose of which is keeping the prongs firmly at closing or opening positions.
Three popcorn bars play role of stoppers for the prongs.
The plug base and cover are not shown.

STEP files of this video:
www.mediafire.com/file/lagocdf9wjj5rsy/FoldingPlugSTEP.zip/file
Inventor files of this video:
www.mediafire.com/file/qkwqj51l0b6w77p/FoldingPlugInv.zip/file