This question comes up here occasionally. Here's what I said last
time:
This isn't a Django issue. It's a standard property of browsers: you
can't set an initial value for file input fields. This is a security
measure, to stop malicious pages uploading files from your hard drive
without your explicit instruction.
There isn't really any way round it, except to do something extremely
complicated like GMail does and upload the file in the background
while the user fills in the form, then replace the file field with a
reference to the uploaded version of the file.
--
DR.