Elements of Biology: Ecosystems: Organisms and Their Enviroment - Movie
Plants and animals compete and cooperate in their environment resulting in what is often described as a "balance of nature" within an ecosystem
Click http://player.discoveryeducation.com/index.cfm?guidAssetId=936f819a-ee6d-4b09-bcb1-40c8d644dc89 link to open resource.