I'll point out, since someone else will bring it up, that composite video cable like that is probably 75Ω impedance. There may be a very slight additional loss compared to using 50Ω impedance cable, but without some fancy test equipment, you'll never notice.
If the cable is good and it does what you need, go for it.
If you already gave the cable give it a go. It won't hurt anything.
As for moving closer, I meant just temporarily, to see if your current reception improves. I wouldn't buy a cable, until I had a pretty good idea it was going to help. If you don't have the cable and need to buy it, get one with 50 ohm impedance.
Just be aware that the 75 ohm BNC connectors are a bit different than the 50 ohm ones and while you can force them you may cause issues. My advice if you still use them it to use adapters so if there is any damage it's only to what can easily be replaced. I use a 90 degree adapter on the scanner end that not only is easy to replace, but also will reduce the stress on the radio connector.