I did that on my last car but eventually had connection problems. I don't like that cigar lighter power supply, it's just bulky and a PITA.
In the end I tapped into ignition (well, key position 1) feed on radio, going to a dedicated power supply for dash cam mounted just under fuse box. Unfortunately I'm getting some DAB interference as the camera is only 6 inches or so from the DAB antenna (mounted on inside of screen).
Going to see if I can improve things using ferrite magnets around power feed. Google says it's possibly a solution.