Make a chunk, "EmbedFlash":
<object ... blah blah... (sorry, I'm not a flash person)
file="[*flashfilename*]" ...
....
path="assets/flash/[*flashfilename*]" ...
</object>
Make a TV named "flashfilename", give it a nice title, "Flash Filename" and description, "set filename for embedded flash object", maybe put a default filename in the Default value field if you have such a flash file, "default.swf", or leave it empty. Make sure your templates that will need this TV have access by checking the checkbox for them at the bottom.
Now, for each document using that template, use the chunk where you want the flash to appear: {{EmbedFlash}}. Edit the "Flash Filename" TV field under the document content field. Just put the name of the flash file, such as "flashlogo.swf".
The chunk already has all the rest of the information needed to embed the flash file. It will be given the value you put as the filename in the TV for that document, and you’re all set.