Magnimas,
It's not really the swivel. More like the tap/slide but instead of a vertical motion, it's horizontal. You kind of imagine that there are two "buttons" to depress, one on the left and the other on the right. You lift up your foot and tap the first button and then quickly lift up your foot again to tap the second button. Hope that's clear enough. Some prefer to go from left to right and some right then left. It's up to you. The whole idea is to alternate the muscles you use. A tip:- use your hip to support your leg after the first tap...don't drop your leg's entire weight after the first tap, otherwise you won't be able to acheive speed comfortably.
Swivel is more like pivoting on one point which some has complained that it causes the knee some discomfort/injury.
Another thing to consider is your pedal adjustment. For me, I find medium loose tension works best for more dynamic use of these techniques. It is possible to execute all the above techniques with tight tension but I find it difficult to vary my volume. It's easier when it's medium loose.
All the best!