These variations are less common than the main 6, but are for the most part, the same tricks applied in sequence, or from a different position.
The mega-round (aka late-9/12/etc) and the scissor each land in the mega position, the only 2 simple variations that do so. Because they are the highest rotation variations (there aren’t really any semi- landing variations to talk about at this time, although this concept can be explored), they can be tacked onto the end of just about anything, assuming that mega rotation and landing can be achieved. Helicopteros are arguably a combination of a swipe or flash, and a mega-round or scissor. Some would argue that helicopteros and “pizzaboys” are different, but for now, they will be presented as the same, as tricktheory has yet to hear a clear, convincing argument distinguishing the two.
The rest of the variations presented are simple variations performed in sequence, such as the feilong (shuriken + round), that can occasionally create their own new terms. Each of these is described in the video before they are demonstrated. These complex variations may not be as popular as others, but they are an introduction to the fundamental concept of stacking multiple kicks in sequence to create ever-increasing complexity.
In terms of our phonetic analogy, what we have now are suffixes. They add something to the end of a word to change its meaning, such as trick to tricks, or tricking.