I've recently seen this video on youtube.

https://www.youtube.com/watch?v=envbbUc4LhU

In my opinion, US tech companies shouldn't be able to do this. The whole "We don't have enough talent in the United States" is obviously a lie.

However, I am willing to open my mind if there are reasons why this should be allowed. 

This is by no means a new problem.

And I agree, there's plenty of varied talent already in the US and thus no reason to outsource. Something like this shouldn't even be considered until literally every individual seeking and able to be employed is, and they're in a comfortable job concerning the earnings (nobody can live comfortably making anything close to minimum wage, and that's before even considering if they live in areas like California or New York).

H-1B is a good concept, and in theory is beneficial to the United States. Being able to retain highly skilled engineers, scientists and entrepreneurs is a win-win situation.
The problem is it they being severely misused. Indian IT companies use them for low-skill jobs in phony companies, and at present Indians alone hog 70% of H1Bs, most of them not the top tier talent the visas are meant to attract. It has become an art for Indian companies.
85000 visas are given each year, but only 20000 are reserved for applicants with advanced degrees from the United States.

Edit: It's also worth noting, high-skill green cards are not subject to this abuse because they have a per country cap, but Indian lobbyists are also trying to rid of it. (https://www.govtrack.us/congress/bills/116/hr1044)

At 4% unemployment, chances are that people with some specific educations are missing. Just look at Germany, where the unemployment rate dropped to about that, too, but where the industry is complaining for years now that there ain't enough people who learned manufacturing crafts like mechanics and electronics, which are thus in very high demand. Probably also one of the reasons why Merkel opened the flood-doors for the refugees in 2013.

However, they shouldn't be able to fire people first on a whim, but that's on US job security regulations.

I'm actually shocked that it isn't already allowed to fire anyone whenever.

Companies should be allowed to hire whoever they want wherever they want.

We really do live in a world where customers want to pay ever more cheaper on products, but earn more as employees and then complain that the math doesn`t match when the companies go hire in another country.

How does this work with unions?

It is in about half the country, in right-to-work states particularly.

I highly doubt that the lack of skilled worker in certain jobs played any role in the decisions she made back than, I also doubt that she wanted so many refugees to come.

"We don't have enough talent in the X-country" This sentence already tells you everything you have to know. Most of the time it is used when your own citizens don't wanna work in certain business because of bad working conditions and low wages.

I's actually the higher paid middle class jobs that require higher education that are missing. The low paid jobs are being taken care of just fine by low skilled immigrants. The problem is that most unemployed just do not have the skill and/or will to get the required education to do those jobs. The more we advance the more advanced jobs we need to perform, but it's not like average intelligence of humans has increased in the past 20 years, but the job requirements sure have.