Whist I don't use the Avast Secure Browser, essentially what mchain is saying is:
It isn't so much the location, but the the means of accessing it, via bluetooth, which is less secure, e.g. if it is outside the Avast Secure Browser.
The Avast Secure Browser is isolated from other applications.
EDIT: You should be able to access youtube if you are connecting to the URL from inside the Avast Secure Browser