There is no video footage in the Throne of the King.

Perhaps the game settings initially have a resolution of 1024*768, and that's why all this mess is happening. But this is just a guess. You could ask someone to upload a save file with the resolution changed to 800*600, or figure out some configuration file. But it's also possible that the problem is of a different nature. Personally, I know that there is "Heroes 5", "Heroes 5: Hammers of Fate", and "Heroes 5: Tribes of the East" is being prepared for release. What is this "Throne of the King"? If it's a pirated version, like the games for the fourth installment of Heroes used to be (D&D or, for example, Alexander the Great), then it's possible that the pirates messed something up with the game, and it won't launch.