1. Launch the game.
2. Choose an episode and wait for it to load.
3. Press Space to pause it.
4. Switch the game to windowed by pressing Alt+Enter.
5. Launch Frontier.exe
6. Press F5.
7. Switch back to the game window.
8. Press Alt+Enter to maximize the window.

Follow steps 3, 4, 6 and 8 again when the black bars reappear at the next chapter.