They are ISIS members caught in the act. Do you think that the Egyptian Army in Sinai is randomly picking up civilians and executing them for no reason? Many of the soldiers are locals from Sinai.
This action, ASSUMING that they are ISIS members caught in the act, is only a bad thing because it was filmed and went public and now is able to be used as a propaganda tool to recruit new ISIS members in Sinai and elsewhere in Egypt.
Otherwise they did Sinai, Egypt, the Arab world and the world a favor. Let dumb Europeans use their methods and let us use our methods. Different world, different reality.
A country like Iraq tried the "civilized" way. In return corrupt judges acquitted numerous terrorists and numerous prison breaks occurred. In return the Iraqi people got more terrorism. Screw "international" law in such a case. Kill the trash on the spot and save lives, time, money and trouble.
Even KSA which is at the forefront of so-called "civilized" rehabilitation programs of former terrorists/extremists (they live in more luxurious surroundings than the best prisons in Europe) have not been a 100% success.