One key benefit of using FamilySearch in FTM 2019 is the ability to seamlessly access a vast collection of historical records and family trees, helping users expand their genealogical research. By integrating FamilySearch with Family Tree Maker 2019, users can compare, merge, and update information with ease, ensuring accuracy and completeness in their family history. Additionally, FamilySearch offers a collaborative platform where researchers can connect with distant relatives and verify shared ancestry, making it a valuable resource for building a well-documented family tree.