BellSouth Prepares Network Upgrade for Video  WASHINGTON (Reuters) - BellSouth Corp. &lt;A HREF="http://www.reuters.co.uk/financeQuoteLookup.jhtml?ticker=BLS.N qtype=sym infotype=info qcat=news"&gt;BLS.N&lt;/A&gt;, the No. 3  U.S. local telephone company, plans to upgrade its network to  offer video services and speedier Internet access to about 80  percent its customers by 2009, industry sources said.