Why the green squares while streaming video?

While streaming video (YouTube, Netflix for example) on my iPhone 5s, the video always falls apart, eventually being covered in green squares or boxes (not a green screen, but more of a glitchy explosion of green squares covering the video). Sound playback is fine, and the video plays without excessive buffering. Updates for software and for the individual apps have been tried. Kind of at a loss of what to try next. It happens while either streaming via wifi or using cellular data, if that means anything. Anyone else experiencing this?