I would get a true NAS. It will use less electric. brands would be QNap, Synology, Netgear, etc.
I would also get at least a 2 drive model to allow for Mirroring. With Mirroring if one drive goes bad Everything is not lost. You replace the bad drive and it will rebuild the array. That is not protection against a virus for example or Oops I did not mean to delete that events.
I am using 4Tb and 2 Tb drives in mine. What that means is that I put in two 4Tb drives to get a total storage space of 4Tb. I also use NAS drives rather than desktop drives. One example of that would be the Western Digital Red 4Tb drives or Seagate NAS HDD ST4000VN000 4TB 64MB Cache SATA 6.0Gb/s Internal Hard Drive.
These are lower level drives, the Enterprise drives are more money.
I just expanded one of my NAS's from 2Tb to 4Tb using two 4Tb drives. I followed the process to replace the drives and expand the space and not lose any data.
Format for the Videos, Interesting question. I have been using MP4 or WMV format for the files.
So If I were adding another one to the network I would be using 2 WD Red 4Tb @ $180 each + $340 for the driveless NAS, $700 + Tax. Not cheap.