As far as ViaCom putting up some of their own content, that is a non-issue smokescreen by YouTube/Google. If somebody loads a couple of trailers to a tube site, that does not give the tube site permission to rip their entire library and set it up for free downloads.
Some main issues:
1) They did not have permission to upload all this content
(~60,000 for ViaCom) to their site, plus all the other ripped content.
2) There are memos, emails, etc showing that they knew what they were doing was illegal, but still continued anyways
3) Their business plan was exposed in the memos, emails, etc. to create traffic using this stolen content and sell the company in a few years at a high price
3) Google executives also knew that ~80% of the content was stolen but still bought anyways. But some of the executives seem to have amnesia about their biggest ever purchase.
Or maybe they simply lost documents in their cloud systems which is really going to be good for marketing efforts. 