What is the function of cytoplasmic filaments? (strands)?

That guy is right in thinking that it is the same as the cytoskeleton. Look up microfilament, intermediate filament, and microtubule. Thier main purpose is to provide structure and motility to the cell, among other things. They're made of protein (mostly actin and myosin) and change their shape under direction of the nucleus. Which is how they provide the movement of the cell and they can move the organelles when needed too.