Learn Russian: Мне нужно, чтобы оператор снимал эту сцену. - I need the cameraman to shoot this scene.

This is the main rule for indirect commands and wishes! When you want or need someone else to do something, you connect the two halves of the sentence with чтобы and use the past tense for the second verb. Even though снимал is grammatically in the past tense, it refers to a desired action in the present or future.

Could I use the perfective verb снял instead of the imperfective снимал?

Yes, both are grammatically correct but they have slightly different focuses. Using the imperfective снимал focuses on the ongoing process of filming. If you used the perfective снял, it would emphasize the completed result of getting the scene finished.

Why does the sentence say Мне нужно instead of using the word я?

In Russian, the most common way to say 'I need' doesn't use a standard verb like in English. Instead, you use the dative case to literally say 'to me it is necessary'. Мне is 'to me', and нужно means 'necessary'.

Why does the phrase 'this scene' change to эту сцену?

It is the direct object of the verb—it is the thing being shot by the cameraman. Because of this, it has to be in the accusative case. The feminine dictionary forms эта сцена change their 'a' endings to 'y' to become эту сцену.