The question is, on a 5" screen will you really notice the difference between a 1080p stream and a 720p stream for video? Especially considering the 720p may be higher bits per pixel than the 1080p stream. I'd rather have a 720p stream at 3/4 the bitrate of a 1080p stream, which is often the case as there are multiple levels for a given resolution.

Then again, I don't always notice even on a larger screen from a better 720p stream and a poorer (relatively) 1080p stream. I often notice the difference from 1080p to 4K though, which is a slightly bigger bump on a much larger screen.