If you are refering to my growler tap, then the short answer is yes. The reason beer goes flat is because the CO2 gas in the beer has to equilibriate with the surrounding atmosphere, whether in a closed or open system. In the case of a growler tap or a kegging system with no external pressure, ie no CO2 applied, the dissolved CO2 is the beer equilibrates with the keg or growler headspace till the pressure in the beer and the headspace are equal. Over time this leads to flat beer, because each time you open it, the CO2 in the headspace equilibrates with atmosphere. This process will repeat till the beer is "flat".
Now this all changes when you apply external pressure, like in a kegging system. By keeping pressure on the keg or growler, the CO2 in beer is on the other side of the equation. The headspace is now at a higher or equal pressure to that of the CO2 in beer. This results in either CO2 dissolving into the beer or remaining at a constant volume of CO2.
So by using a growler tap you can apply pressure to keep the beer carbonated similar to a kegging system. When you want to dispense beer you just open the tap and apply a little pressure to get beer to flow. When done drinking for the evening, just apply a little extra pressure and place in the fridge.
But yeah...its all magic. Pay no attention to the man behind the curtain.