Flash Movies should be used on a webspace for one of two reasons:

1. To get a specific point across
2. To draw the audience into the page

If one is employing the second reason, a skip button should be available on the page.

There is nothing more annoying than seeing the same Flash movie over and over again with no recourse - it will make people avoid the page.

Below is a design of awell-donel Flash/Splash page.  Notice the bypass button.

Well-designed page

 

As in this site, design of a Flash movie should be integrated with the rest of the site. The movie should be short.