1. In informal spoken English, speakers sometimes leave out words, but the left out words are "understood".
2. The speaker may have been speaking very quickly and it sounded like the "are" was left out.
How're you doing?
But, it may have sounded like:
hau wer ya du win --- blending "how, are, you" into "hauerya"...
I'd have to hear the clip to know which one happened here. Just know that spoken, informal English is just that: informal. It is not a good example of good, 'textbook' formal English you learn in English class. The speaker probably (we hope) knows standard English, but, this style of informal English is common in everyday life.
Student or Learner