WD UI / Media feels dim or not bright enough

You can try going into the WD audio/video setup and manually set the color space value. Select HDMI and set the resolution/frequency to something that your TV supports (such as 1080i, 60hz). On the next screen you can set the color space. For most TVs using the HDMI input, RGB Low is the correct choice, however, with your symptoms, RGB High might work better for you.