First she took this year’s Super Bowl halftime show by storm and now Beyoncé has hit the high note on cable. The singer’s co-directed Beyoncé: Life Is A Dream documentary was watched by 1.8 million HBO viewers Saturday in its 9 PM premiere. That’s a 10-year audience high for a documentary on the premium network. In 2004, Nielsen changed the way it determines viewership on HBO, so prior-year comparisons are apples and oranges. The closest the cable station had to such numbers was in 2006, with the Spike Lee directed When The Levees Broke: A Requiem In Four Acts. That film documenting the aftermath of Hurricane Katrina on New Orleans pulled in 1.7 million viewers. Beyonce had a good night on another network also on Saturday. The singer’s 8 PM interview on Oprah’s Next Chapter pulled in 1.3 million viewers on Winfrey’s OWN