Export Flash from Adobe Premiere Pro 1.5
Unfortunately it is not possible to export Flash files directly from Premiere Pro 1.5 (this feature was added in version 2.0). However it is possible to export from Adobe After Effects, with one big proviso: You must also have Macromedia Flash MX Professional 2004. This version of Flash comes bundled with Flash Video Exporter, a utility which plugs into many popular editing applications.
After installing the Flash Video Exporter you can go to After Effects and find a new option in File > Export which allows you to export Flash files.
Note: There is another option for creating Flash video files called Sorenson Squeeze. For more details see Using Flash for Streaming Video.