I'm sure the methods they are using and advertising in their video are extensively protected by patents that can be searched here: "Graphene Production" patent search
Remember that it is just a promotional video, and what they say is not necessarily true.
At 1:11, "...100 times better conductor than copper..." Not likely:
2500 W⋅m−1⋅K−1 Graphene/ 385 W⋅m−1⋅K−1 = only 6.5 times better it turns out.
At 1:24 "...and the middle is completely cool." I find it quite unlikely that even an exotic material like graphene can conduct heat without becoming that temperature ;-)
This phys.org article explains that the crystals must be aligned. "When two crystals are neatly lined up, heat transfer occurs just as predicted by theory. But if the two crystals have mis-aligned edges, the heat transfer is 10 times less."
In the past I have cut ice with low grade pyrolytic carbon that I originally procured for a diamagnetic demonstration. The very high conductivity is quickly evident and it works just like it does in this youtube video.
On the graphene wiki article:
"Early measurements of the thermal conductivity of suspended graphene reported an exceptionally large thermal conductivity of approximately 5300 W⋅m−1⋅K−1, compared with the thermal conductivity of pyrolytic graphite of approximately 2000 W⋅m−1⋅K−1 at room temperature. However, later studies have questioned whether this ultrahigh value had been overestimated, and have instead measured a wide range of thermal conductivities between 1500 – 2500 W⋅m−1⋅K−1 for suspended single layer graphene."
As far as economic feasibility; there would have to be some major reductions in price and increases in conductivity to make it more economically advantageous than current geothermal fluid heat transfer systems; let alone other forms of power production.
MIT, Technique for mass-producing graphene
MIT, Continuous rolls of graphene
PopularMechanics, Mass producing graphene