Some symbiotic relationships are mutually-beneficial. The term for such relationships is "mutualism". Mutualist relationships are ubiquitous in biology. Some videos illustrate the phenomenon in the organic world:
Ant and caterpillar symbiosis.
Acacia Tree Ants.
Leaf cutter ants and fungus.
Clownfish and Sea Anemone Partnership.
Elephants Are Terrified By Ants .
Ant Caterpillar Mutualism.
Perfect Symbiosis - tree ants.
Coral Reef Symbiosis.
Evolution coevolution of the ant and fungi.
Ants farm aphids.
Tree Ants & Caterpillars.