My one annoyance in all versions to date, including the Alpha, has been that the video pop out doesn't have its own window like it did in MX5.
You either have it popped out always on top or not all all. I very much prefer to be able to have full screen videos playing but be able to switch to something else without putting the video back in. I get that this is some sort of Chromium thing as it's the same as the Chrome pop up player but I definitely preferred the Maxthon version.
Along with the seek bar and controls as requested above.