Five must-watch videos: A digital currency arms race; Trump's comments on rich advisors; and a factory that runs itself

From an arms race in digital currencies to a factory that runs itself, here are five must-watch videos handpicked by CNBC:

Here's what sets ethereum apart from its rival bitcoin

Cryptocurrency ethereum could potentially prove more lucrative than bitcoin. It's been flying in bitcoin's shadow, but investors are taking notice of its powerful financial technology.

Which explains why ethereum prices have soared nearly 4,000 percent so far this year to more than $322. Bitcoin prices have surged too this year, but some investors and companies think ethereum's underlying technology could make it a big part of the financial industry.

Trump: 'I just don't want a poor person' running the economy

Speaking at his campaign-style rally in Iowa on Wednesday, President Donald Trump told the crowd he chose wealthy, proven business people to top economic positions because they're better at managing money.

"I love all people, rich or poor," Trump said. "But in those particular positions, I just don't want a poor person."

This start-up is using robots and 3-D printers to build a factory with almost no humans

A Brooklyn, New York-based start-up called Voodoo Manufacturing is developing a factory that can 3-D print almost anything, and without human overseers.

Voodoo is developing robots to run the 3-D printers, its CEO told CNBC. Customers can upload design files to Voodoo's website, which sends the files to the start-up's 160 different 3-D printers.

This giant Amazon beehive drone warehouse could pop up in your city someday

A recent patent filing from Amazon depicts what could become the fulfillment centers of the future — giant beehive-like structures filled with delivery drones.

Of course the patents may never exist outside the drawing board, but they do demonstrate how Amazon is thinking about the future of drone deliveries.

Jack Ma: In the next 30 years people will work 4 hours a day

In an exclusive interview on Wednesday, the founder of Alibaba, Jack Ma, told CNBC that artificial intelligence and widespread automation could shorten the workweek to four hours a day, and maybe four days a week.

"My grandfather worked 16 hours a day in the farmland digging," Ma told CNBC's David Faber. "He thinks he is very busy. We work eight hours, five days a week. We think we are very busy."