The article is well worth reading (and not terribly long), but the high points seem to be:
-- YouTube knew perfectly well that most of their content was pirated, *and* actively avoided doing anything about it so that they could drive up their value, *and* Google was entirely aware of this when they bought the company.
-- Viacom has engaged in a lot of sleazy hypocrisy, screaming bloody murder about their content appearing on YouTube while engaging people to go and put *more* of it up. (For publicity, and possibly to strengthen their hand in a lawsuit.)
Nobody comes out smelling of roses from this one. It'll be interesting to see the end result. If all the allegations are true, it sounds like Viacom is right that Google knew about infringement and wilfully ignored it, but Google is right that Viacom deliberately muddied the waters to the point where there was no practical way for Google to do much about it...