I've been experimenting with bitrates and the effect on video quality. As I up the bitrate my Go (and others) occasionally play at higher than 1x speed. You can hear it in the audio also. I can "fix" it by pausing or restarting. Seems a bit random. Video with rates around 10Mbps play fine. Much above that the issue starts to happen. The source is mp4, 4K, stereoscopic.