Most of the time it will show me options up to 1080p or 1440, but almost never 4K even when 4K is available and will always show in Chrome. Is Google trying to get us to use Chrome, or is this down to Safari? Here's an example: 4K60 in Chrome, 1080p60 in Safari. (Amazing video btw!!) This is on my MBP 15" TB 2.9Ghz model.