Doing that kind of a test, you can fire the balls into the corner pockets on a 6 x 12 snooker table as well, just like on your table. The shot you're demonstrating is a one in a million type of shot, because of the use of 3 balls in a combo, you're eliminating any chance of throw, spin, as well as running the balls straight down the face of the cushion into the deepest part of the facing and back of the pocket.
Try this, line up only 2 balls in a combo, then fire them into the pockets. Then while you're doing that, start putting a little throw into the shot by hitting the 2 ball combination a little off center...so what you're doing is injecting a little error into your shot...as when you're actually playing pool, that way you can see the difference in how balls are pocketed when they come off the rail at a slight angle, hit the facing farther out, hit the rail further up yet still be inside the pocket.
In other words, replicate shots you actually make on a table, because no one can miss a 3 ball combo down the rail...even with 4" corner pockets
Glen