Yeah, no problem. Just shut down the power and proceed with your illicit activities. Be sure to video tape yourself and link to it here,
Thank you,
mangeorge
You can buy a 2tb hard drive for about $150.00 now a days so you could store a weeks worth of images then rerecord over it without that much cost.
As others said, stores care about their employees getting shot, but they are less concerned with catching a thief. After all they are insured. Often part of the requirement for insurance is that they have a security camera. Nothing says it has to be a GOOD system though 
It varies. A well-designed system will have camera power supplied from a central location with some sort of UPS backup. Sometimes this isn’t feasible, and cameras are powered from local sources. Theoretically you could unplug these, but it would be less effort to spraypaint the lens or whatever, so it’s not really a critical vulnerability.
Also, depending on the situation, the cameras can simply be hard to get to.
As noted though hard drives are cheap these days. You can get multiple terabytes of storage for a song and a dance these days. For a business you could easily buy all the storage you need for two weeks of video at high quality with multiple cameras for a few thousand dollars. Cameras are pretty cheap now too.
Unless you have a need for really long term storage of months of video from many cameras it should not be all that expensive, considering it is a business no less, to pull it off.
Heck, save your ass from one lawsuit will probably pay for it all and them some.
These days!
But most of the systems in stores were installed years ago. That’s why they mostly use VHS tape recorders. And generally, stores don’t replace them until they are completely worn out. No particular benefit to the store; most of them are never robbed. You get a discount on insurance for having a system, any system. And stores usually don’t spend money if they don’t have to.
Our GE DVR is from late 2004, so there might be some technical issues, but I suppose there should be a way to hook up an external hard drive.
I use a GE software program to view my business over the internet through the cameras, too. That’s sort of neat.
telephones business
“Hey, employee X, why are you in my chair with your feet up on my desk?”
There is a local downtown pet-sitting operation that has similar software. You can go on the internet and link to various cameras they have around the area, and see your dog playing with other dogs, sleeping in his bed, eating his lunch, etc.
Apparently quite popular with the pet owners.
Huh. Perhaps they should get that for daycare centers, too.
You can get this at home too, two-way video and audio. I’m not sure what your pup will think of your disembodied voice with no “daddy” smell. 
As others have mentioned, the Issue is usually not the quality of the cameras, especially for more expensive setups ( More the $50-100K)but the quality of the recorded video.
One of my friends helped setup and maintains a security system for a pretty high profile location and one of the points we discussed was that while the realtime video is incredibly (Just below HD in some cases) storing it at that quality would be cost prohibitive, when you factor in the number of cameras and the amount of time they need to keep the video stored and available.
Do keep in mind that while Consumer HD’s have come down in price many of the High end systems use SCSI drives for reliability and speed, end even those which use SATA more often use the higher quality, more expensive 10,000 RPM drives as they need the faster speed to be able to record more video. Also, Most store Video in a proprietary compressed format which often necessitates using proprietary hardware.
As such, if I Remember correctly they usually store most feeds at 320x240 at 15fps which is a little higher then usual but what they need to get usable footage and have enough space to have record all their streams for 1-2 months.
Some info on the open source tools for this are here: What are the moving rectangles in this security video? - Factual Questions - Straight Dope Message Board
It’s one thing to set up a motion-detection video system and have it record only when something’s going on in your building at night without using terabytes of disk space, but when you’re watching an incoming stream of cars at the car wash or customers at the bank, motion capture is going to be nearly pointless as you’ll have eight, ten, however may hours of pretty much non-stop motion to capture.
That’s almost $100 of storage!!
You can copy over the images after a day or so if there is no reason to save them.
I know someone who is a marketing consultant for a hi-dev security camera company, and I’ve seen stores where they are in use so companies do use them.
I can only assume the grainy, black and white, blurry images you see of Home-Boy robbing a liquor store in the Bronx are because it’s an old, cheap CCTV system recorded on a VCR or something.
If something happened that required reviewing the recording, wouldn’t you realize it within those four days anyway?
They do. One of my coworkers can check up on his daughter
via the web.