I take some of it it back: I was testing locally.
Online, depending on how you set Safari's security preferences, Quicktime is invoked and the pages play ok.
Locally, it's still no go: doesn't matter how you set the "user agent" in the developer menu— 6.1, ff etc—it doesn't play. Suspect it's something I still haven't sussed out.
Why Safari ? I'm primitive: I liked Firefox's old 'error' console, which has been buried deep in the developer menu in recent versions. Safari gives me immediate chapter and verse if I make an error (most often a typo in the js or something equally basic).