please help me with downloading movies <3

I started downloading movies and TV shows so my dad would have something to watch when he travels. Through the FMHY website and the megathread I found a firefox extension called Video DownloadHelper. I keep encountering this issue where the extension only wants to download a trailer, even when I'm actively watching the movie. This mostly happens on Cineby. I tried another website from FMHY, FMovie, and that one actually lets me download the movie, but it's so insanely slow. please help me figure out what, if anything, I can improve on. Also please keep in mind that I am stupid. I do not know how to torent and frankly I'm a little scared of it. please ELI5 everything

some extra details-

I'm on Mac. Thanks to this sub, I've been mainly using Firefox. I have tried various streaming websites and different downloading tools. My options are limited from being on Mac, using firefox, and once again, being stupid. I have uBlock Origin and Privacy Badger extensions. I use a free version of Malwarebytes and I have paid for Avast Cleanup, both recommendations from Apple support.

I am once again reminding you that I am very stupid. I don't know what Kb/s means or how to test it, I don't understand torrenting, I don't know how to set up a VPN...... please be nice to me