Is "as" necessary here?
That's a great question. The use of "as you know" is literal. It says that I recognise that you're already aware of what I am saying. In the case of this clip, I recognise that you already know who my favourite designer is. Since that is what we are wanting to convey the "as" is necessary. If we were to remove "as" and simply use "you know", it is no longer literal. In this context "you know" is something between an attention getting device and a pause word. When it is used like this, you can usually substitute it with "actually" and convey the same effect and meaning. Ex: As you know, this needs a lot of practice. Ex: You know, this needs a lot of practice.
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