The following services provide you with legal locations for downloading and viewing Ben 10 episodes. They can be played on various devices.
iTunes
Ben 10
Ben 10: Alien Force
Ben 10: Ultimate Alien
Ben 10: Omniverse
Movies
Ben 10: Race Against Time
Ben 10: Alien Swarm
Ben 10/Generator Rex: Hereos United
Amazon Instant Video
Ben 10
Ben 10: Alien Force
Ben 10: Ultimate Alien
Ben 10: Omniverse
YouTube
Ben 10
Ben 10: Alien Force
Ben 10: Ultimate Alien
Ben 10: Omniverse
Google Play
Ben 10
Ben 10: Alien Force
Ben 10: Ultimate Alien
Ben 10: Omniverse
Cartoon Network
You can find episodes online at the following location.