So, I've been converting a lot of old home videos and have loaded the hard drive on my mac pro.  I have a 500GB with OS X, photos, etc.  A 500GB and 1TB drive with movies, and a 2TB drive for time machine.  I'm getting to capacity and love using time machine as backup, but seems like 2TB is the largest time machine can be.  Looking for some other backup options.  Was thinking maybe stick with using time machine for all backups except movies, the just mirroring drives as backups for movies?  Two 2TB drives in the tower for movies, and an external NAS that mirrors them?  Tnx.

You can use any hard drive as a time machine. You do not have to have the Apple sanctioned one...

Yes, I am using all internal WD enterprise drives, I don't have the apple one.   Thing is, 2TB is the largest single drive and I don't think splitting time machine among a number of drives is a good idea (as well as I believe there might be a 2TB file sizes limit for time machine back up files, but am not 100% on this)