hi there, i have a brand new MacbookPro 2018 and find it does some semi-irregular flickering when playing back videos. Sometimes it does a little, sometimes it's full Poltergeist mode. Other times, playing the same video under the same conditions, it plays back normally. I've seen these problems arise with and without external peripherals. It's a new 2018 MBP running High Sierra (10.13.6). Any thoughts? thanks!