itch.io will be forcing HTTPS everywhere starting next week.
Here's what you need to know: http://blog.itch.io/post/134343623599/switching-to...
Everything served by us will be updated. It looks like that error is because we're generated a HTTP URL for the SWF file. I'll get a fix out.
Looking at Midboss's page, they're not blocked, but for example, Chrome's "https lock" isn't green, it's gray, and clicking it reveals why: mixed origin resources.
I know github has their own https proxy for images embedded in markdown files they render for example, perhaps we could do that?