Save the DVD! AT&T's Warner Bros. and Universal shake hands on deal to sustain the humble disc

The DVD – once the must-have in family rooms around the country – is getting some much-needed help from two unlikely partners.  Warner Bros. Home Entertainment, part of AT&T Inc. (NYSE: T), and Universal Pictures Home Entertainment, a unit within Comcast Corp. (NYSE: CCZ), unveiled plans for a proposed joint venture for distribution of physical discs in North America. The rivals, which both have huge libraries of movies, say the unusual step needs regulatory approval.  The push comes as…