This is not a very good guide. First, it's the Campaign Map, so the enemy AI goes after your main unit first even in lower ages, unless it's out of range. Second, the one real unit is a Hover Tank, which hides on plains, so the Battle Fortresses are going to hit Rogues regardless of what you do unless they're close enough to move adjacent to a Hover Tank. Third, the only reason the Plasma Artillery (which ignores stealth) hits a Rogue instead of the Hover Tank is because the Hover Tank was out of its range due to terrain. Therefore, you haven't shown us anything except that you misinterpreted your own video.