From video description:

In this video I take a look at turning PLA 3D prints flexible by bathing them in Carburetor Cleaner (also known as carby cleaner).
The results were amazing, but, I don't feel they are worth the potential dangers. Carby Cleaner is very toxic stuff that is highly flammable, not good to breath in, not good to get on your skin and the smell lingers on for ages.
Definitely do not give the parts to kids as I don't reckon putting these parts in your mouth afterwards is a good idea at all.

http://www.nulon.com.au/products/Aerosols/Throttle_Body_and_Carby_Cleaner/