I have often used Flash to create graphics movies to be used as elements inside a video edit. I would typically publish a quicktime from my .fla file and import that quicktime into Final Cut Pro, including movies with a transparent background (alpha channel).
These days that is not so easy. Somehow Flash 8 will not export a usable quicktime from a .fla file that contains embedded symbols such as movies or transparent layers. (Adobe claims that the Flash CS3 upgrade will export to Quicktime with effects).
Upon export Flash 8 will prompt you to set to export at Flash 5 settings, which is not always usable if you have layers with filters on them that are only supported in Flash 8. Embedded movies (symbols) will not export properly either. The workaround is simple actually: use Snapz Pro X.
- Publish your .fla as a .swf movie with format settings at Flash 8. Be sure your JPEG quality is at 100%. If you are exporting with the view of going to video make sure your document background and frame rate have the correct settings (720 x 480 for full resolution NTSC / 30 fps). Publish your movie then open it with Flash Player on your desktop, making sure you are displaying it at 100% size with quality on High (View menu).
- Open Snapz Pro X, click on the 'Movie' option. Adjust your selection window to include the full window of the Flash movie and give yourself a little bit of a border around it as well. The Flash movie should be playing back in looping mode. Set the Snapz capture window at Framerate :30/ Color Change: millions/ Scale: 100% and check the Smoother Video Capture radio button (turn off the Cursor Visible button). Press return to capture the movie, letting it loop a couple of times.
- Stop the record. In the Movie saving setting window click on the Settings button. Change the export settings to Compression type: None / Frames per second: 30 / Quality: Best. It is important when going to video to use None as your compression setting (in Quicktime as well) this will afford you the best resolution throughout your post-production workflow. (None is a better setting to use than 10 bit uncompressed ! Oh, and never, never, never use the Animation codec!!)
- Save your movie.
P.S. If you need a transparent background, I would suggest making your Flash movie on a clean blue background and using the Keyer in Final Cut Pro.