Yup. But there's more to it than meets the eye.
The trick is the connectors, not the cable. Regular RCAs are usually 50 ohm and no amount of trickery will solve that. The only 'certified' 75 ohm connectors I know of are the Canare RCAs.
FWIW, I have two digital coax cables, one is a 3m run using regular microphone patch cable with Neutrik RCAs on the end, connecting the onboard soundcard of one of my PCs to an AVR for a gaming surround system. The second is a slightly better cable for a PC-DAC connection in my main music PC, built with 75ohm coax, but 50 ohm RCAs from Amphenol. The second cable performs slightly better, but I know there is some more potential for improvement. I had bought a ton of the cable and some connectors to experiment with optimal cable length, but have not found the time to get down to it.
Basically because of the impedance mismatch between conductor and connector (and input terminal) there is a reflection of the transmitted signal at the junction where the mismatch occurs. Longer cables alleviate this somewhat in case they are not properly designed in the first place (though it's a band-aid). Someday soon I'll have more concrete first-hand evidence of this and a report on whether all this is actually audible or not, which is the big Q. In the meantime, I suggest not worrying about it.
Subwoofer cable is analog. Totally different ball of wax. TV coax is *not* recommended for analog applications as the impedance is too high, and the capacitance will kill most of the sound, and can damage audio preamplifiers.