If a regular TV doesn't have a coax input, it must be an antique, as coax has been standard for decades. If this is the case, you'll have to get a balun to convert from coax to the twisted pair input. If it's not an ancient TV, please describe what connections it does have.
Some luggable TVs don't have ANY connections, just one or two telescoping whips.
Perhaps, but I've had a couple of those, over the years, and both had a short piece of cable, from the antenna, coming out of the back and onto a coax connector. If you wanted to use the built in antenna, you'd leave that short cable connected. If you wanted to use an external antenna or cable, you'd unplug that short cable to make room for the connection. However, I didn't get the impression that's what he was referring to. For that matter, I didn't get much of any impression, because he didn't provide any useful info.