Is my understanding of quasi-causality and virtuality correct?

Deleuze distinguishes between corporeal causes and incorporeal quasi-causes and associates the latter with the concept of the virtual. This is my understanding of those concepts:

Virtuality is neither mere possibility nor actuality. Actuality is something that exists in its full form while possibility is simply something that could exist because it does not contradict itself. Possibility is purely conceptual, what is possible is simply what does not contradict itself. The virtual is something in-between because, on one hand, it exists (like the actual), but on the other hand, it doesn't exist 'in its full form', in other words, it has not actualized itself.

An example of the virtual would be the plant in a seed. The moment you plant a seed, if you feed it water, leave it in the sunlight and wait a few years, it is bound to turn into a plant. The plant here is not just a mere possibility, something that could happen, it's something that already exists within the structure of the seed. The plant is the actualization of the seed. So the plant is therefore not just possible, but virtual the moment you plant a seed, since it already exists, just not in its 'complete form'.

Quasi-causality in my understanding is related to virtuality. A quasi-cause is when actuality stems from virtuality. A quasi-cause is neither a sufficient, nor a necessary condition for its effect. For example, we hear that smoke causes cancer. But this is not necessary, as you can smoke and not get cancer. And it's not sufficient either, as you can get cancer without smoking. Thus, smoking becomes a quasi-cause for cancer. In this way, cancer is the virtuality of smoking, it's not just a mere possibility, but something that follows from the act of smoking, something that already haunts the presence of smoking like a ghost, something that exists in the act of smoking itself but that just hasn't actualized itself.

Did I understand virtuality and quasi-causes correctly or am I completely off?