Feature summary (what you would like to be able to do and where):
I would like the ability to be able to upload from a website directly into Commons’ Upload Wizard.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
When using other file uploaders in other websites, there is usually an option that allows you to directly upload from a website instead of your computer. I was surprised to see that this wasn’t an option on the Upload Wizard. I initially chalked this up as to stop copyvio spam, only to realise that this was indeed an option in the standard upload form. Upon further inspection, I realised that it only allowed uploads from whitelisted websites. I see no reason why this can’t be implemented in the default uploader. The solution would probably resemble something like this:

with an error message popping up if you upload from the wrong website.

Benefits (why should this be implemented?):
It doesn’t require you to use your computer as a middleman when uploading from a website, which is great if your computer’s internet speed is low, or if you have a limited amount of data or storage.