-The video shows Margaery with combed and clean hair but wearing a much more demure and conservative dress than the lowcut dresses she usually wears.
-This points to her allying with the High Sparrow to probably get out of prison as well as a way to control Tommen since the high Sparrow has been brainwashing Tommen lately.
-Loras has shorn hair and is wearing rags which points to him also maybe joining the Faith Militant and also allying himself with the High Sparrow.
So basically, Margaery is pulling Cersei's season 5 move of pretending to be devout and religious of allying herself with the High Sparrow to get out of prison (even though unlike Cersei, Margaery has an army willing to fight to rescue her) and for power and control since Tommen is starting to get swayed by the High Sparrow. And I'm sure just like Cersei in Season 5, it will all work out 100% well for her.