Hardly a solution - I just explained how to get rid of the app that doesn't work. The app still doesn't work and we still can't watch DirecTV on our Macs.
I opened an issue with DirecTV support and the last reply I got was:
...I have forwarded your information to our directv.com support team (engineers) for further research and resolution. Our team will work diligently to correct this issue for you as quickly as possible. While we are unable to provide a specific timeframe for resolution, I will personally follow-up with you as soon as this is resolved or if additional information is requested...
This was back on 25 February, a week ago so far.
Maybe if more people filled out the "email support" form on direct.com we'll get some pressure on them.