http://lifehacker.com/hola-better-internet-sells-your-bandwidth-turning-its-1707496872
TL;DR: Running the Hola Unblocker application turns your connection into a public exit node on a P2P network. It allows people can to use your Internet connection and potentially access illegal material.
Well fuck I never knew this. Thanks for this post! I'm going to uninstall HU now.