The PBS Video channel on Roku offers an "Up Next" feature. This feature automatically plays a new video once your currently viewed video has concluded.
This feature can be disabled after a video by selecting the Dismiss option on the left side of the "Up Next" prompt or by exiting the current video before 30 seconds have passed.
If you wish to disable the feature entirely for the channel, open the Settings menu at the top of the PBS Video channel home screen. Select the Continuous Play option to switch it to Off from On. You can return to this Settings menu at any time to turn it back On.