Update a public upload on your account with the specified parameters. Don't forget to specify PUT as the request method as GET will call the show action rather than update.
https://streamio.com/api/v1/encoding_profiles/upload_id.format
PUT
204
Just remember to PUT and you'll be fine.
curl -u username:password \
-X PUT \
-d "title=AwesomeCampaign&tags=awesome,campaign" \
https://streamio.com/api/v1/uploads.json?id=4c483ea1bf4b9802c5000029