Learn Italian: Usiamo la telecamera perché ciò non succeda. - We use the camera so that this does not happen.

In this sentence, perché means "so that" or "in order that" to express a purpose, rather than "because" to express a cause. When perché indicates purpose, it requires the subjunctive mood.

How would this sentence change if I wanted to say "We use the camera because this doesn't happen"?

You would just change the verb to the indicative: Usiamo la telecamera perché ciò non succede. Changing the verb's mood completely flips the meaning of perché from purpose (so that) to cause (because).

Could I use affinché instead of perché here?

Yes, you could say Usiamo la telecamera affinché ciò non succeda. Affinché also means "so that" and always takes the subjunctive. It is a bit more formal than perché, but it removes any ambiguity since it can never mean "because".

Why use the pronoun ciò instead of questo?

Ciò is an invariable pronoun meaning "this" or "that" when referring back to a whole situation, abstract concept, or action. You absolutely could use questo here, but ciò is very common and natural when referring to an abstract event happening.