No, notarization is not a requirement for a valid will in California. You do need at least 2 witnesses to have signed it. These witnesses must be "disinterested", which means they are not only not beneficiaries, but also not named executor. Basically, the will would need two people who are not related to the person who made the will and whose names do not appear in the document. If they have witnessed here it would meet the requirements of the law in California to be admitted.