The song is "story of tonight" (workshop) from Hamilton
(The video above is not mine and is only being used for audio)

"I may not live to see our gory-"

"I may not live to see out gory!"

"But I've seen wonders great and small~"

"I've seen wonders great and small ~" 

"But if the tom cat can get married-"

"If Alexander can get married~" 

That's all I have now, but it'll probably be done tomorrow x3