Don't worry if you didn't get it. tbh this isn't a great explaination, especially the way it tries to go into things like offside before it's done the basics. And the whole two versions thing.
It's actually not as messy and complicated as it might seem.

A rugby union team consists of 15 players, divided into Forwards (1–8) who contest set-pieces and rucks, and Backs (9–15) who handle attacking play and defense. Positions are numbered 1-15, typically split into a Front Row (1-3), Second Row (4-5), Back Row (6-8), Half-backs (9-10), Centres (12-13), and Back Three (11, 14-15).
(16-23 is replacements)
Forwards (The Pack)
Forwards are generally larger and stronger, responsible for securing possession.

1. Loose-head Prop: Part of the front row, binds on the left of the hooker in scrums.
2. Hooker: Throws the ball into lineouts and hooks the ball in scrums.
3. Tight-head Prop: Part of the front row, binds on the right of the hooker; vital for scrum stability.
4. & 5. Second Row (Locks): Tallest players who provide power in scrums and jump in lineouts.
6. & 7. Flankers (Blindside/Openside): Fast, aggressive defenders who secure the ball at breakdowns.
8. Number 8: Controls the ball at the back of the scrum and links forwards and backs.

Backs
Backs are faster, more agile players responsible for running, passing, and kicking.

9. Scrum-half: Links forwards and backs, acts as the primary passer from breakdowns.
10. Fly-half: Dictates play, makes tactical decisions, and is often the primary kicker.
12. Inside Centre: Strong runner/tackler who plays close to the fly-half.
13. Outside Centre: Agile, fast runner with good passing skills to create space.
11. & 14. Wingers: Among the fastest players, responsible for finishing attacks and scoring.
15. Full-back: The last line of defense, skilled in catching high balls and counter-attacking.

You did OK, no worries about looking silly etc. Find Best Rugby tries, best teams eg Springboks (South Africa) or All Black's (New Zealand. Video's on all time modern players are amazing as well. For Rugby League (I haven't followed so much in recent years), but anything on Australia's team or their clubs match's are amazing to watch. Good luck with expanding your channel.

Rugby fan from South Africa here (our national team, the Springboks, are the world champs!)
You should definitely react to "The Most Feared Rugby Team In The World | The Springboks Are BRUTAL BEASTS" if you want to see not only great defensive tackles, but excellent offense and overall team synergy.
Rugby Union is more fun to watch, in my opinion, as it's a lot more kinetic (as opposed to stop-start) and action-packed!

rugby union is the more popular version

The Tush Push by the Philly Eagles derives from the Rugby Union scrum, as a Rugby Union coach was hired by the team.

hello

Have a look at this highlight next: https://www.youtube.com/watch?v=V6IRIN0g6gU   (I have no idea if they'll strike you for reacting to it so just make sure you cover yourself). After that, i'd recommend a full match: https://www.youtube.com/watch?v=5I8WhpKusM8
DO NOT react to that one, you are likely to get a strike, just watch in your own time to get a better understanding of how a game flows.
Good Luck, and welcome to the world of Rugby.