Edit: I should have read the whole thread before writing this, Old-Lumens already said it.
They are using moving fluid instead, our blood to be exact. Same way as warming your hands by holding a cup of coffee. Makes me wonder, if we’d insert some plexi glass tubes, filled with water or oil, similar to the ones used in spirit levels 
, into the pill/heat sink, either horizontally or lengthwise like you’d attach trits - would that make a difference?
Speaking of differences, the thermal conductivity of silver grease doesn’t exceed 10 W/mK*, our potting compounds may not exceed that by much.
In case of ‘flat top’ drivers such as the ones shown in post #8 Potting Drivers - Budget reversable option? regular heat sinking using flat base copper or alu rounds would be 20-40x more effective *².
The gap below that level/between the compounds could be filled with potting mix; thermal glue or grease on top to make contact to the HS, just as usual.
For uneven, but similarly simple layouts (like pic 1 from the linked post), a fitting shape could be achieved by either filing or metal casting using a wax mold*³ - even tin, which can be melted on a stove, has way higher conductivity (66.8W/mK) than thermal grease. You’d need a parting agent - talkum, silicon grease, maybe a layer of plastic foil, to enable easy removal of the wax.
‘* Thermal paste - Wikipedia
’*² Solids, Liquids and Gases - Thermal Conductivities
’*³ Metal casting a custom heat sink (chances are you wouldn’t have to bake the mold as much for tin casting)