What happened at the end of Trading Places?

I present to you, the tail end of what I do on my lunchbreak sometimes.

Trading Places
No, not the show about remodeling...
The Oscar Nominated badass 80s movie.

So, with the economy taking a downturn...I suddenly thought to myself "I wonder if anyone online can explain to me exactly what happened at the end of Trading Places

You know, the famous scene at the end where they somehow manage to become millionaires off of Orange Juice?

Thank god for the internet, 'cause this guy figured it out!!!

Trading Places: How Winthorpe and Valentine Pulled It Off