Dealing with video these days usually means working with lots of data, and when you're working with a lot, it usually means you're backing up even more. One solution for backing up is to buy drives that already come in a RAID (like the popular G-RAID, and another is to either purchase or make your own with bare drives (and yes, before going further, RAID itself is not necessarily backup depending on how it's configured and where the physical drives are). If you're going to be putting together your own RAID system, click through for which drives might be a good buy.
Thanks to Backblaze for doing the heavy lifting, we've got an idea about what you might want to be looking at if you're building your own system. It should be noted that Backblaze is running these hard drives through the toughest situation possible, but they should be a good indicator of the kind of performance you'd get: