This is a solution to a problem for which I was unable to find any tips in the App Inventor resources. I have a set of videos and each time I click the “Next” button I want to auto play the next sequentially numbered video (without user manually starting it). My initially wrong approach was to have the button listener set the video source and call VideoPlayer.Start. Eventually I guessed that setting the video source causes some background loading to occur so it’s necessary to introduce a delay in the program before calling Start. This I achieved with a timer set to one-tenth of a second.
When “Next” is clicked it sets the video source and enables the timer. When the timer fires it starts the video and turns itself off.