Hi,
Cubase 8.x video engine is based on Quick Time. So if you can playback the video in the Quick Time player, you should be able to play it back in Cubase too. If you cannot play it back in Quick Time, then it’s on Quick Time side.
As you might know, Apple doesn’t support Quick Time on Windows anymore. So no one knows…
Cubase 9.x uses its own video engine. You could try to download Cubase 9 Trial, and test if you can open your video file here.