For a start, the currently supported Video formats for Flash
are Sorensen Squeeze and On2 VP6. As far as I know, both of
those companies are actively fighting Free implementations
of the codec. That makes Flash video as bad or worse than
VC-1. You can play all 3 of them with FFmpeg btw.
As for the things you mentioned: The Flash spec is semi-open, in the sense that you may not use it to write an interpreter for Flash. That's equivalent to closed for everything you care about. And the spec covers the file format only, not the video formats used or what script objects are supported.
And you can populate Flash files using remote data. You can even chose between XML and Flash. The XML needs to be interpreted, but I'm pretty sure there's convenience libraries for you that do that.
And it's not like the Free alternatives are far behind in the game. HTML5 has a video tag and SVG is far superior to anything Flash offers in drawing options. Especially because it's scriptable while Flash shapes are not.
There's 2 things missing:
- Simple animation support: Flash makes creating animations extremely easy. Doing the same thing in anything Free (HTML, SVG, even Gtk) requires being a good code monkey. The example above required NO coding.
- Authoring tools for rich web applications. Depending on who you ask, the best Free authoring tool is either vim or emacs. There's the Gimp and Inkscape of course, but neither does animations nor scripting, so it's pretty useless for doing rich web apps.