Was watching the Boulder Cup the other day and noticed what looked to be Shimano shifter cables routed underneath the bartape. Is that what I am seeing in this pic? And if so has anyone tried it out?

Yes they are looped. This person is trying it out obviously, using Nokon housings.

a teammate of mine did it on his road bike using nokons as well. he had even less housing out in the loop than that picture depicts.

it works fine, and he has routed it like that for a few years now i believe