I was unable to reproduce any problem on that page; the cart appears in front of the embedded video for me in all browsers tested.
If you're still seeing the problem, you may need to force-refresh the page in your browser to be sure it's loading a fresh copy of the page and everything on it direct from the server, rather than showing you a cached copy from a prior visit. Hold the Ctrl key (on PC) or Shift key (on Mac) while you click the Reload/Refresh button (or just hitting Ctrl-F5 on a PC does the same thing).