iframe YouTube video stopped working

Today, all iframe YouTube videos stopped showing up on my site on all four browsers I test. I didn't make any changes to anything having to do with any of that, just a few minor updates to logo images, style sheets, etc. My site features videos from relevant items on its main page, but the embed code is also no longer working on item-show pages. Could this be a Windows-wide thing just on my machine? I tried adding the domain to trusted sites in my Windows settings, but I'm unclear if that just has to do with IE. I'm using Omeka 1.51 and usually Firefox (18.02 now installed), but Chrome, IE 8, and Safari all do the same thing. The site is at http://ourmus.net.

I can see the iframe'd YouTube video on your front page just fine. A few items/show pages with videos worked fine, too.

Maybe you have a problem with Flash, or a problem connecting to YouTube from that computer?

Never mind. I restarted and eventually the videos started showing up again. I still don't know what happened, though.