Looks like squiggly fine piping to me.

I thought that at first also but when I looked closely they are almost floating around the tier.  Any suggestions? 

1. real grapevines
2. wires

Looks like to me, because it's floating,  that it's a version of the royal icing "cage method".

I don't know for sure though...what do you think?

Probably real grapevine, but you could certainly use a fine rope die in your extruder, and form the curly parts separately around a toothpick or something round.

This is part of Collette Peters' class that she teaches via Craftsy.com.  I bought the class but haven't watched it yet.  Think it's piped chocolate but I wouldn't swear to it.

The cage method is what I was thinking but didn't know what it was called.  Just wondering how do I to attach it?