My experience...
The dip swirl works like in the above videos, but you can't use acrylic paint. You must use ENAMEL paint. Enamel is sticky, but fluid and it floats on top of the water. I've been using the cheap way (enamel spray paint sprayed into the cap to collect, then poured into the water and borax mixture). I've yet to use proper liquid enamel, which is what is used in the above videos. Try it with spray paint over a white primed enclosure. It's fun!