To me, what stands out in Gareth Bale's goal versus Southampton is how he lulls the defender to sleep for a second and then blows past him at speed. It's the stopping and starting motion that throws defenders off and keeps them on back heels.
There's no fancy move or a thousand Cristiano Ronaldo step overs, it's all about Gareth Bale's change of pace. Bale takes a few slow dribbles of the ball right at the defender, and then explodes past him on his favored left foot.
The key his how Bale takes a touch of the ball with every step when he's dribbling at the defender. It's a skill that he may have mastered via this soccer drill. Take a look at the goal in the video below. Easy to say, but how and why does the defender let Bale cut inside?
And here Gareth Bale uses his speed to sprint past defenders and score a goal from his own defensive half - all the defender can do is try to push him out of bounds with his shoulder, but the defender can't even do that. Highlight collection of Bale's speed and goal scoring ability.