my miller tig set makes some weird noises too. It is normal. I cant really hear much on your video to be honest but the rear sounds similar
The sound became lower i guess it is from compressing video for youtube.
Here is the the machine without cover, and me testning to turn the machine off slowly...
That sounds really bad! My XMT doesn't sound anything like that, it's utterly silent! Sometimes makes a slight squeak when stick welding, that's it!
My on/off switch is slightly weird though. It wants a good positive push to turn off, or it will crackle like there's a loose connection.
Have you located the component making the noise?