Multiple effects causing extra phases in M:tG
Medomai adds turns, not phases, so the rule you quoted isn't really necessary. Assuming no blockers, here's what happens:


Medomai attacks on your turn. Finest Hour's abilities trigger.
You can stack Finest Hour's abilities in either order. Assuming no other actions, Medomai is now 5/5 and there is now a combat phase after the current combat phase.
Medomai deals damage. Medomai's ability triggers, so you take an extra turn after this one.
You get another combat phase. Medomai attacks again, gaining another Exalted trigger.
Medomai deals damage. Medomai triggers and you get another turn after this one (and before the other extra turn, not that it matters)
You take two consecutive turns in which Medomai can't attack. Each of those turns can get a bonus combat phase from Finest Hour if you have non-Medomai creatures to attack with.