Mary: The Immaculate Conception

Why do Catholics believe in Mary’s Immaculate Conception? Is there any Biblical support for this doctrine?  

Here’s a video clip from my teaching in Nazareth on the Immaculate Conception for the Mary study:   https://m.youtube.com/watch?v=bqeUpvMXLk8

Filmed inside the traditional site of Mary’s home (From “Mary: A Biblical Walk with the Blessed Mother” – Ascension Press)