The "trick" being discussed is the dissolve (aka cross-fade). The article covers this form of scene transition solely from a story telling and aesthetic viewpoi

The "trick" being discussed is the dissolve (aka cross-fade). The article covers this form of scene transition solely from a story telling and aesthetic viewpoint but the technical craft of dissolves is also interesting because there are many different types. Simple dissolves have a constant linear velocity to the alpha blend but in S-curve dissolves the velocity changes with parameters sometimes called ease-in and ease-out. In sophisticated editing software these curves can be controlled with various types of splines. Although the rate is changing, even relatively short S-curve dissolves often feel subjectively smoother to viewers than linear dissolves because more of the duration is dedicated to the beginning and ending phases which tend to be more visually subtle. In addition to varying velocity dynamics there are many other interesting and useful types of dissolves such as alpha blended wipes, luma fades, strobes, holds, black/white dips, flash fades and a variety of temporal effects. How an editor chooses to deploy these tools can either make them feature elements or merely subtle tonal flavors. In the early days of non-linear video editing tools there was more development put into creative transitions but recently editing tools tend to offer only a few dozen canned transitions. This requires editors to use separate visual effects software to achieve more sophisticated or subtle transitions. This inconvenience is one reason such effects are less common outside high-end productions although another driver is that the insufficient bandwidth often dedicated to streaming compression tends to degrade any type of visually subtle transition into a macro-block mess. This is especially unfortunate now that higher dynamic range, bit depths and frame rates are widely available to visual story tellers.