Teresa Waters/Wizarding Movies

Procuring the Memories

 * The people who "film" the movie are the bystanders watching from the side. These bystanders must remain as motionless as possible and pay close attention to the scene.  They must also be capable of extracting their memories.  When the desired "scene" is "filmed", the memories of 6 bystanders should be extracted for manipulation.

Editing the Memories

 * The memories must be edited to preserve a realistic scene; that is, the memory mustn't look like a set, but a true memory. Manipulating the memory with certain spells will accomplish this.  These manipulations can take place when the memory is in the palm of one's hand, though for most of these enchantments it is more prudent for the memory to be handled while inside a Pensieve.

Diffindo

 * The simple spell Diffindo is traditionally used to cut or rip the target. In the form of memories, the spell is used to cut out any part of the memory that does not belong in the scene; for example, the bystanders.  This is a delicate process, as the wand is moved in the way the bystanders should be cut out; it is easy to mistakenly cut out a piece of wall as well.  As the memory as shown in the Pensieve is shown from many different angles, the empty space left by the bystanders is naturally filled.