I don't know everything either! Not even close! But I did just write a paper on the 144,000. I have three observations for you to consider about this passage in Revelation 7.
First, why is the list of the 12 tribes wrong in v. 5-8? There is no tribe of Dan listed, and it includes Manasseh, which is not a tribe of Israel. It also leaves out Ephraim, which is not a tribe. So Joshua and Samson, both from Ephraim, will not be in heaven? Could it be that this list is not about Jews, but is symbolic of the complete number of God's redeemed?
Second, it says in v. 4 that John 'heard' the number of the sealed. How do you hear a specific number? Could it perhaps be symbolic? In the culture of the day numbers were significant. 12 tribes, 12 apostles, this symbolizes completeness. Twelve, or multiples thereof, is a number of completeness/fullness in the book of Revelation -- much like the number seven. This number may signify the complete number of Jewish believers in the end times -- joining the complete number of saved Gentiles, cf. Romans 11:12, 25-27 -- all of which make up the one Church of Jesus Christ.
Third, after John 'hears' the number in verse 9 it says that he 'sees' them. And this time it is a "great multitude that no one could number, from every nation, from all tribes and peoples and languages.' This is the same group as two verses earlier! 144,000 was John's way of symbolically describing the complete number of God's redeemed from every tribe and nation.
My point is, maybe you're wrong, and that's ok. I'm willing to be wrong as well. But, you have to convince me from Scripture, not from a youtube video! (which I did watch by the way).
"Be a listener only, keep within yourself, and endeavor to establish with yourself the habit of silence, especially on politics." -Thomas Jefferson