Thanks Jetrell!
Made a test clip - x264 10mbps 81MB: https://fs06n2.sendspace.com/dl/51c0a7eb5cc191e003be1f34f09b7734/583976f827ad7a8a/d90hzt/EP1_deleted_scene_04.mkv
I managed to take screenshots (with the “stamp” key) from both NTSC DVD and my encoded x264 version, using MPC-HT as player: