This is one of the most powerful testimonies I have ever heard.
I add to my testimony wholeheartedly to Elder Holland's. I know the Book of Mormon: Another Testament of Jesus Christ is the word of God because the Holy Ghost has borne witness to me over and over again of its truth and authenticity. I invite you to study the words of this book and discover for yourself whether it is true (the full text is also available online). For, "by their fruits ye shall know them".