I'm looking for the name for the plastic connectors you can see in https://www.youtube.com/watch?v=nwAZbA3yUoU&t=39s (at 0:39).
They consist of an outer part that can be squeezed together and put into the hole that you want it to go into, and then an inner part that you push into the outer part. The inner part then forces the outer part apart, which causes the whole thing to firmly stick in place.
In the video, the inner part is partly pulled from the outer part. The connector is used in a Renault Clio 3 to lock the front apron in place (together with what feels like a myriad of screws). I broke one of them during my attempted disassembly and would like to replace it…