The feature he is referring to is called "Geartronic" by Volvo. It has several different names by other manufacturers like Tiptronic, Autostick, etc.

This feature allows you to determine upshifts and downshifts by pulling the gear lever over to the left into another gate. Once in this the shifts are commanded by pushing forward or backward to upshift or downshift respectively. You will find that for normal flat road driving that this feature's novelty will soon wear off. It is fantastic for mountainous driving where you may be on roads with switchbacks where you are on and off throttle and the trans is shifting too much and can't seem to be in the right gear at the right time.

On an electronically controlled auto trans the control unit makes the determinations for shifting based on an array of inputs. When you place lever in geartronic position you command the activation of the solenoids that engage the various gears.

The only auto operation done in geartronic mode is auto selection of 1st if you stop while in a manually selected higher gear.

It also won't let you downshift ot a gear so low as to make engine speed excessive if it were selected.