Can't Center Images

Image at bottom of post not centering: post URL is https://nowthinkaboutit.com/2013/12/the-big-rush-moses-mabhida-stadium-swing/

I’ve struggled with centering images forever. Any help resolving will be appreciated. The Theme is old and I suspect that is part of the problem. I have fiddled with the CSS and probably made it worse.

One other problem: The YouTube video at the beginning of the post is also not showing for some reason.

Thanks for any help.