Header image off center and unresponsive since recent (?) update

Hi, I haven't looked at my website since a month or so, but I now see that the header video is totally out of whack: It is uncentered, not aligned with text, a huge white space in text, the play button is off-centered and when resizing the browser it does neither move (so disappears if browser borders are dragged over it). It used to be flush and tight above the text, so something has changed, but I cannot find out what. No settings or CSS have been able to solve it so far. The site is:. www.stephenwhitmarsh.com I would really appreciate some help.