Yes, 7200rpm and 64mb cache would be considered good.
I think for a primary / operating system drive, one should get a fast drive. Period. I used to always pick 7200rpm drives over 5400rpm drives and extra cache for that reason. Then for mass storage, with infrequent access, top speed isn't critical. The world in hard drives has changed a bit though, in that with the number of platters, platter density, etc. rotational speed isn't necessarily the key factor any more. Density and platters can be (low density 7200rpm drive vs high density 5400rpm drive). Of course these days. Forget about 120MB/s HDD speed for a primary drive. Now we're moving 300MB, 400MB, 500MB per second with SSDs.
Back to hard drives. Does one need an above average hard drive to record video data? Possibly. It will depend on the number of cameras and how much data each camera stream requires to be written to disk, either in 24hr mode or motion detection mode. Motion detection, one can think well that's just a moment here and there, when somebody walks past or drives up. That's what I thought. Until I set up my first camera; and the wind starts blowing and branch shadows dart across the property, rain starts falling, snow starts blowing, ... The cameras don't distinguish between weather and people. Movement = record. So, the more channels you have, at the higher resolution; the more you need some headroom for recording when all cameras suddenly require it.
I've always liked tom's hardware. This might be good to glance at:
http://www.tomshardware.com/charts/hdd-charts-2013/-04-Write-Throughput-Average-h2benchw-3.16,2904.html
It'll give you a quick idea on some common drives, the fact that rpms aren't the sole speed factor, etc.
PS: In my testing I am seeing a 3mp camera set to 1920x1080 at above average quality settings in h264; produce streams at about 1MB/s. Depends on what they see, fps, etc. Right now my little system is looking at four of those streams, maybe tweaked down the settings a little towards average and network data in is 2MB/s. I"m not sure yet how/when exactly a hard drive becomes the bottleneck; if streams randomly want to be stored to hard drive and things start queuing up. Right now I"m trying to see what my little core i5 machine is doing cpu and heat wise; while keeping 4 streams on display.
