The book of Ruth is traditionally read on Shavuot because almost the entire story takes place during the time of the harvest, which leads up to Shavuot. Shavuot is a holy day that was created by God to take place at the end of the spring harvest to celebrate and give thanks to God for the harvest and to return our tithes and offerings from the harvest back to God.
This movie is very well done and sticks to the Biblical account very well, highlighting and quoting word for word some of the most significant phrases from the book of Ruth.