chrispiac

I think it is a QuickTime Problem. Depending on Version of QuickTime and OS X 5.1 audio is not able for Playback. On some OS X Versions it is possible to fix the problem with the „Audio-MIDI-Setup“ program (Programs -> System Utilities -> Audio-MIDI-Setup). Most of the Mac can only play Stereo on internal speakers, so 5.1 audio isn't necessary. When you connect your Mac to external 5.1 speakers you can configure it with this Setup program, usually the sampling rate or some other parameters are not correctly set.

France will change from DVB-T to DVB-T2 (with AVC/h.264 Codec) till beginn of year 2017. Some areas will chance earlier and reduce the power or switch off  DVB-T transmission in 2016. So you stayed in a region where DVB-T is in France not longer avaiable. Some basics in france about „television numerique terrestre“ : http://www.telesatellite.com/television-numerique-terrestre/