Ustream.tv negotiating $50 million sale to Microsoft

Sources tell Valleywag that lifecasting startup Ustream.tv is in advanced discussions with Microsoft to acquire the lifecasting service for more than $50 million, but there are other companies in the bidding as well. Ustream is currently raising a very large initial round of VC financing, and Microsoft is attempting to grab them prefunding for a cheap price. Our tipster also mentions that Microsoft would use Ustream as a way to promote its Adobe Flash competitor, Silverlight.