VideoPlayer: Dropping frames, but frameDropped event not getting called

I'm having an issue on the device (iPhone 6). The video is very clearly not playing all the frames - it's choppy and stuttering. The timestamp in the UI is advancing smoothly and XCode is reporting a steady 30fps, indicating that the game itself is running at the expected framerate. To me, this clearly indicates that the VideoPlayer component is dropping frames.

The movie is 720p, 24fps, h.264 encoded, 237 MB total - nothing that should give an iPhone 6+ any trouble. It is being rendered via a RenderTexture on a quad. On another test project, the same video plays smoothly when playing directly to the screen (camera back plane), so I suspect that the RenderTexture has something to do with it.
UPDATE: I've switched the app to use camera back plane and it has the same issue. Could this choppiness be memory-related?

This line:

Code (csharp):

1. videoPlayer.frameDropped += (source) => { Debug.Log("VideoPlayer: Frame dropped at "+Time.time);}
2.  

... should ensure that frame drops are accompanied by messages in the console, but I have never seen a single frame drop message.

I've attached screenshots of XCode showing smooth, steady performance... but the video is anything BUT smooth.