How does a Recommender System recommend movies to a New User? Consider a New user which has never rated any movie on the Website or the System has never seen the user.

How does the System recommend Movies to the User and based on what ? 
How will we evaluate the Recommendation , is the recommendation accurate or appropriate and how confident the system is about the Recommendation .
In general, a safe default option for recommender systems is to recommend the most popular product, so two options for the recommendation:


simply recommend the most popular movie in a time window around the current moment (maybe taking into account momentum),
do the same but marginalizing over account info, e.g. age, gender, country, language; also, IP location is an option to get such type of info.


Confidence assessment can be done based on recommendation success rate over the results of the same recommendation to previous users with the same profile characteristics, if such data is available.