This is a bug in Chrome using the pepper plugin: https://code.google.com/p/chromium/issues/detail?id=137734
What's happening is that the trusted locations (set here: https://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager04.html) aren't taken into account, so any Flash <-> JS interaction is broken.
It doesn't look like this bug is getting fixed (judging by the comments on the issue today, there's a good chance it'll get marked as a "Won't fix"), so for now there's 3 ways around it:
- Use another browser - not ideal
- Use the NPAPI plugin - the pepper plugin is the default, but it's mostly a set-once-and-forget sort of task
- Run a local webserver - either something like apache (http://www.easyphp.org/) or node (http://nodejs.org/). This is Google's preferred method of dealing with this, as it more closely mimics network behaviour (including security stuff)