If all you want the drive for is HD video storage, I'd go with the 2TB. I've got a 1TB and 1.5TB in my main system, and it got full with only a few hundred movies and about a dozen TV shows (all episodes). Going to buy 10TB more once prices get back to normal later this year or early next.
I don't like deleting things. I guess you could call me a digital hoarder.
All my drives are 7200RPM. Both were home to games at some point, and I needed the throughput. Now that I've got 184GB of SSDs in my system, all they do is store media. If I were buying the drives today, I'd go with whichever drives got me the most storage for my money. Maybe spend 10% more or so to get slightly faster drives just so I wasn't scraping the bottom of the barrel on performance.