Ok, this the secret to the bonus mystery trick.
The top has the axle joining the upper and lower tips, both set as bearings tips. But I discovered that if you turn both tips in opposite directions, so both try to unscrew from the axle, the pressure from the axle will make the tips freeze. The lower tip gets fixed well, so you can use it as a regular fixed tip. However, a little torque on the upper tip will unstuck the setup and both tips will become bearing again. I don't know if this happens with all Giulias with upper tip kits, or just on this one.
The idea of the trick was to have first a fixed-tip-only trick and finish with a bearing-tip-only trick, with a upper tip trick in between to accomplish the magic. There, I found a use for the axle (besides keeping the cap from popping out)!
Disclaimer: this is an out-of-specs use of the tops and may damage the tips. I got scared a couple of times when the lower tip did not spin well after doing this, but it was just some bad alignment of the parts. I wanted to get it on the video, but I don't know if I am doing it again.