you only need to use the h.264 source that would play anything on any device. it can be a mp4 3gp avi or webm it will run on ios and android. but that is what i know from C2 not sure if is applying to C3 now.
if is not working try setting the source of the video when the intent of playing the video is happening by saying if player pressed play video button load source h.264 filename with extension then play. it will take a while for it to preload or buffer. but if is inside the project should start in 1 second max.
it might be that using the free version might have some limitations on exporting the project with the video plugin.