I think, I finally found an answer to the question, why one should use Flash instead of HTML5: Binary sockets

Newer Flash Player versions allow developers to open binary socket connections, which is not possible using pure HTML5/JavaScript in the browser (HTML5 only supports websockets, which are different).

Thus, for example, it would not be possible to create a FTP client without Flash or a backend system since such an attempt would require one to open a socket in order to implement the FTP protocol.

I think, I finally found an answer to the question, why one should use Flash instead of HTML5: Binary sockets Newer Flash Player versions allow developers to open binary socket connections, which is not possible using pure HTML5/JavaScript in the browser (HTML5 only supports websockets, which are different). Thus, for example, it would not be possible ...

Tags: Adobe, Ajax, Flash, Flex, HTML, In English, JavaScript, Rich Internet Applications, Webdevelopment