Fair warning: It is very dangerous to make statements like this in a public forum like this.
You run the risk of someone spotting it and making a seemingly-innocent reply along the lines of, "Oh, you should at LEAST have TWO disks set up as a mirror so you don't lose all your movies when (not if, but when) the disk dies." And then someone else will say, "LOL u noob, RAID not a backup!" Another participant will assure you that no data is safe unless it's stored at on at least a 5-disk ZFS array. And then someone else will jump in to point out that even ZFS is not safe if you're not running ECC memory. And course you can't just have ONE of these ECC-enabled 5-disk ZFS-breathing monsters, because every component ASIDE from the disks is a single point of failure, so you'd better have TWO just to be safe. Which means you'll need a UPS because sudden power loses are _awesome_ if you like having your platters scribbled all over by a browned-out disk controller. And what exactly is your disaster recovery plan in the event of a fire or flood, gotta have some infra running in good health off-site in case something like that happens. And so on.
Of course if you dig far enough into these admonitions and suggestions, the good news is that you won't have the time to watch any of those movies.
Weight off my shoulders!
Resilvering might take ages. So long that raid2 might be mandatory.
I haven't calculated the right risk factor but I still only use 4tb disks
Good enough for me, I assume it's way more likely that a PSU failure fries them all, in which case no variant of raid would have helped anyways. For important stuff I have an off-site Backup, but that's only around 800gb anyways and growing a few gb per year.
Beyond that, hard drives are cheap! I have a single 18 TB disk in my main computer that runs Plex. It lets me and my kids watch content from anywhere with an Internet connection.
18 TB hard drives are about $300.