If you say a word a certain way as this is saying then you should have no issues getting in. If it is like a fingerprint and using voice recognition at the same time as using lip reading software then it could be very difficult to break the password.
.. Why?! This just seems like a horrible idea. It uses cameras, which is just no good - especially with the NSA and CIA spying like they are (See Wikileaks Vault7). There's no way I'd ever use that kind of tech. I don't even do anything really wrong - I just don't buy into the "It's no big deal if you have nothing to hide" philosophy.