I saw a video of Ronaldinho do this trick ages ago for Gremio and saw a few others doing it recently so decided I'd give it a go. After quite a bit of practice I can pull this off quite often now and thought I'd share it.
From the "Joy" Joga Bonito Ad
This is the vid of Ronaldinho doing the trick I stole from Croationblood1 so credit to him and thanks
This is Wilhelmsson doing the trick
When I started learning it I watched the video of Ronaldinho doing it as I thought his was by far the best looking version, though probably hardest too. He seems to get more movement and exaggeration than Wilhelmsson. This is what I got. I find this particular move easier with my right foot so left-footers switch the instructions.
1. Begin standing behind the non-moving ball (to begin with). Then step forward quickly and plant your left leg in front of the ball leaving enough space for the ball to pass behind that leg.
2. Now "catch" the ball with the instep of your right foot and drag it behind your standing leg. Don't push too hard or you'll lose the ball.
3. As you do this you should be leaning slightlyleft and your weight be on your standing leg. This makes more room for you to flick the ball round and back the other way.
4. As you're dragging the ball move your foot round to the other side of the ball and plant it on the outside of the ball. When you plant your foot try and have the entire sole of your foot touching the ground so that you are kicking your foot flat with a snapping motion.
5. If done correctly the ball will flick back in the opposite direction. Ole
As you get better at the move plant your foot (1.) further to the left of the ball which means you will have to drag the ball further and it will be harder to get the ball around your standing leg, but the movement will be greater and it will look better and wrong-foot the defender more.
I've found the most important thing to pulling the hocus pocus off is the angle of your feet. For example, if you're right footed you should have your feet and body turned to the right. Once you do this you'll find the hocus pocus is no problem. You might even say it's easy.