In order to replace factory plug and play BNC Connector and DC Adapter plug for a High Definition Swan Camera in an return air plenum, we have replaced the factory cable with an cat 5e cable recommended to use with the Video Balun and DC Adapter to connect to the DVR. Are there any reasons why the Video signal does not work? Do inexpensive Costco cameras require an RG59 Coaxial Cable?
Inexpensive Costco cameras probably won't be real HD. Real HD cameras will be IP based (ethernet) or SDI coax, which is rediculously expensive isn't really seen outside of casinos. It's almost certain that your cameras are regular analog and
should work with baluns.
As noted above, baluns are polarity sensitive. Assuming the cameras are 12VDC, the power would also be polarity sensitive. I've used baluns from Nitek, Muxlab, and Gem, and the easiest ones to work with are the ones that have an RJ45 jack and break out the power themselves. The most recent ones I've used are Gem BLN-PVRJ45 which have an LED indicator for power. (cheap too)