Why would Vimeo video play on iPad via Read It Later but not in Safari?

I maintain a site that includes video embedded from Vimeo, which I've been disappointed to see doesn't play on the iPad (though not suprised, after all, because "Adobe Flash is the underlying technology that makes Vimeo videos play, and keeps the moon in orbit"). But after installing the new Read It Later app and trying it out a bit, I was surprised to find that the same video on this same site actually plays when viewed in Read It Later:



Any ideas on why that would be the case? Can you view the video embedded in this post in Safari on the iPad? How about using Read It Later?

I know that Vimeo is planning to roll out HTML5 conversions of videos, so perhaps that's how it works on Read It Later? I just noticed that I can view the video within Safari on its vimeo.com page, which makes it even stranger that it isn't viewable when embedded on another site.