Not so long ago, who would have thought that an HBO movie would ever play the Cannes Film Festival? Times have changed. Steven Soderbergh’s “Behind the Candelabra,” made through the premium cable channel after Soderbergh couldn’t find an interested U.S. distributor, screened last night at Cannes to a enthusiastic reception – there’s even talk that Michael Douglas might win the fest’s Best Actor award, or that the film could take the Palme d’Or for best picture. “Candelabra,” which depicts the relationship between flashy Las Vegas pianist Liberace (Douglas) and his much-younger lover Scott Thorson (Matt Damon), will air on HBO Sunday. I won’t miss it.