When the court ask for uploader info,,,
 

What stops the defendant from giving a list of made up IPs or the IPs of people that sent them DMCA notices and says there the illegal uploaders :disgust

How many of the uploads were by investigators? How many of the IP's on the list do they KNOW will exist if they're given the real list? Spanning how many months or weeks?

Lawyers generally dont ask question for which they dont already have the answer.

In theory, prison.

I'll add that also it might be possible to verify whether those IPs even accessed the site in question and when depending in the ISP's log retention policy. Then again, if they are smart they could use proxies.