Captivate outputs no longer working

We are having almost this exact issue. We have a series of training computers set up in a lab environment for customer training.

Because the network connection in this lab is somewhat sketchy, we have created local copies of all our training modules. Sure enough, after IT pushed an update, all modules with embedded video (.mp4, flv, f4v, and ogg) ceased playing those videos. The module will launch, but the slides with videos will just sit there. All of these modules were working fine previously. Incidentally, modules without video appear to be working fine. This problem occurs both in IE and Chrome.

TEMPORARY WORKAROUND
Publishing the modules as HTML5 works, though its not actually solving the issue for why the modules suddenly wont work.  The main drawback here is that any swf components like custom player skins, slide transitions, some variables actions, and swf animations will not play. Fortunately for us, most of these video modules are really just used as interactive packaging for the video itself. Anyway, it appears that modules have to either be all HTML5, or all .swf.

I am almost 100% certain this is a browser flash player issue. Republishing everything is not an option because we have hundreds of training modules out there.

I am hoping someone at Adobe can help out with a solution for flash player.

I'm having similar issues. Many of my courses are linked together via buttons with "Open URL or File" actions.
These linked courses are published and residing in their proper places. I know this because they were working about a month ago. Now, all of a sudden, none of these actions are working. Even on courses that were finished and working. I am in the development stage of a new project and was struggling to get this action to work, so I went back to an older course that was working - same problem now.

Anyone know what should be done, or what might've changed?

You just updated the OS (Windows 8.1), which may have triggered updates to the browsers.

When authoring in Cp, stability is your friend! 

Updates should be planned, as they'll possibly cause courses to behave differently for users.

If your organization has a central IT group, it's best to try to coordinate with them to understand their update plans and timing, and get a pulse for the 'flash plugin' life-cycle.

I'd imagine we'll soon start to see horror stories of IT removing Flash without warning and causing massive course incompatibilities.

You'll want to manage updates to your authoring systems, as well as the users OS, browsers and plugins.

Can you check if Flash is not blocked by Chrome? And I heard that the latest Flash player has indeed issues with Chrome as well, even if SWF output is not blocked. Not an answer, I know.