I'm just a simple caveman lawyer, and your world of finance frightens and confuses me. However, it sounds like Viacom wants a refund on a substantial bonus it paid to Harmonix's founders.
Long story short, Harmonix was bought by Viacom, the parent company of MTV Networks, in 2006 for $US175 million plus "earnouts", which is a jargony way of saying "beat previous figures and you get a premium". In this case, Harmonix got $US150 million based on 2007 performance, and some $US300 million overall since then. However, Viacom in this filing notes that the $US150 million payment was subject to adjustment.
While Rock Band has done some $US1 billion in revenue since 2007, sales of its games have sagged in the past year. So now Viacom says it believes it's "entitled to a refund of a substantial portion" of that payment, although the final amount is TBA.
Viacom Asking For ‘Substantial' Refund on Harmonix Earnout From Founders [Paid Content]