The following are quotes from our Savior Jesus Christ and also from the prophet Mormon. I hope the reader spends time parsing and pondering them:

3 Nephi 20:14 And the Father hath commanded me that I should give unto you this land, for your inheritance.
15 And I say unto you, that if the Gentiles do not repent after the blessing which they shall receive, after they have scattered my people—
16 Then shall ye, who are a remnant of the house of Jacob, go forth among them; and ye shall be in the midst of them who shall be many; and ye shall be among them as a lion among the beasts of the forest, and as a young lion among the flocks of sheep, who, if he goeth through both treadeth down and teareth in pieces, and none can deliver.
17 Thy hand shall be lifted up upon thine adversaries, and all thine enemies shall be cut off.

And

Mormon 5:19 And behold, the Lord hath reserved their blessings, which they might have received in the land, for the Gentiles who shall possess the land.
20 But behold, it shall come to pass that they shall be driven and scattered by the Gentiles; and after they have been driven and scattered by the Gentiles, behold, then will the Lord remember the covenant which he made unto Abraham and unto all the house of Israel.
21 And also the Lord will remember the prayers of the righteous, which have been put up unto him for them.
22 And then, O ye Gentiles, how can ye stand before the power of God, except ye shall repent and turn from your evil ways?
23 Know ye not that ye are in the hands of God? Know ye not that he hath all power, and at his great command the earth shall be rolled together as a scroll?
24 Therefore, repent ye, and humble yourselves before him, lest he shall come out in justice against you—lest a remnant of the seed of Jacob shall go forth among you as a lion, and tear you in pieces, and there is none to deliver.

The Lord brought a great many Gentiles from their mother lands to inherit the promised land (America) and they swept away all those who were occupying it. Now the Lord is bringing a great many more and they shall sweep away all those who are now occupying it. A righteous remnant from both groups will remain to build up the New Jerusalem.

3 Nephi 20:20 And it shall come to pass, saith the Father, that the sword of my justice shall hang over them at that day; and except they repent it shall fall upon them, saith the Father, yea, even upon all the nations of the Gentiles.
21 And it shall come to pass that I will establish my people, O house of Israel.
22 And behold, this people will I establish in this land, unto the fulfilling of the covenant which I made with your father Jacob; and it shall be a New Jerusalem. And the powers of heaven shall be in the midst of this people; yea, even I will be in the midst of you.

And

3 Nephi 21:22 But if they will repent and hearken unto my words, and harden not their hearts, I will establish my church among them, and they shall come in unto the covenant and be numbered among this the remnant of Jacob, unto whom I have given this land for their inheritance;
23 And they shall assist my people, the remnant of Jacob, and also as many of the house of Israel as shall come, that they may build a city, which shall be called the New Jerusalem.
24 And then shall they assist my people that they may be gathered in, who are scattered upon all the face of the land, in unto the New Jerusalem.
25 And then shall the power of heaven come down among them; and I also will be in the midst.
26 And then shall the work of the Father commence at that day, even when this gospel shall be preached among the remnant of this people. Verily I say unto you, at that day shall the work of the Father commence among all the dispersed of my people, yea, even the tribes which have been lost, which the Father hath led away out of Jerusalem.

The board is set, the pieces are moving. Who will be around to assist the remnant of Joseph who was brought out of Jerusalem to participate in building New Jerusalem?

Ether 13:5 And he spake also concerning the house of Israel, and the Jerusalem from whence Lehi should come—after it should be destroyed it should be built up again, a holy city unto the Lord; wherefore, it could not be a new Jerusalem for it had been in a time of old; but it should be built up again, and become a holy city of the Lord; and it should be built unto the house of Israel—
6 And that a New Jerusalem should be built up upon this land, unto the remnant of the seed of Joseph, for which things there has been a type…
10 And then cometh the New Jerusalem; and blessed are they who dwell therein, for it is they whose garments are white through the blood of the Lamb; and they are they who are numbered among the remnant of the seed of Joseph, who were of the house of Israel.

And

JST Genesis 50:24 And Joseph said unto his brethren, I die, and go unto my fathers; and I go down to my grave with joy. The God of my father Jacob be with you, to deliver you out of affliction in the days of your bondage; for the Lord hath visited me, and I have obtained a promise of the Lord, that out of the fruit of my loins, the Lord God will raise up a righteous branch out of my loins; and unto thee, whom my father Jacob hath named Israel, a prophet; (not the Messiah who is called Shilo;) and this prophet shall deliver my people out of Egypt in the days of thy bondage.
25 And it shall come to pass that they shall be scattered again; and a branch shall be broken off, and shall be carried into a far country; nevertheless they shall be remembered in the covenants of the Lord, when the Messiah cometh; for he shall be made manifest unto them in the latter days, in the Spirit of power; and shall bring them out of darkness into light; out of hidden darkness, and out of captivity unto freedom.

These numbers shown in the video are probably underestimated.