Is there a difference between Byte serving PDFs and Progressive Downloads of Videos?

[alflow]

Hi,

I am trying to write a jack-of-all-trades file-serving script (said files are in a folder outside the web-root).

Can anyone tell me if there is a difference between byte-serving PDFs and progressive downloading video files (e.g. FLVs and WMVs)?

If there is a difference, how should I code for it?

This has stumped me for quite a number of days now - so help is greatly appreciated.

Thanks
Alfred