HID RELAY PROBLEM - rattling

Hi everyone,
I recently installed a DDM Tuning HID kit. Since then it's always been making a strange sound when I turn the HIDs on (but the lights are working fine).

The relay base is physically vibrating and making a strange sound, see the video below:
DDM Tuning HID Kit Relay Rattling - YouTube

What is the problem and how can I fix it? I'm not sure if this is safe or not! I did the install correctly.

Thanks