JOEL - For LDS members the word "scripture" not only refers to the 4 Standard works of the Church it can also be described as "whatsoever [God's representatives] shall speak when moved upon by the Holy Ghost" (D&C 68:2-4; cf. 1:38; 2 Pet. 2:21; 2 Tim. 3:16). Therefore, anyone who is moved upon by the Holy Ghost while speaking in General Conference and recorded for later reading in the Ensign, including the First Presidency messages, are considered scripture, although they would not be included as part of the Standard works of the Church.
As explained in the Book "Gospel Principles":
"In addition to these four books of scripture, the inspired words of our living prophets become scripture to us. Their words come to us through conferences, Church publications, and instructions to local priesthood leaders." (Gospel Principles Chapter 12)
And President Joseph Fielding Smith said:
"What is Scripture? When one of the brethren stands before a congregation of the people today and the inspiration of the Lord is upon him, he speaks that which the Lord would have him speak. It is just as much scripture as anything you will find in any of these records and yet we call these the standard works of the Church. We depend, of course, upon the guidance of the brethren, who are entitled to inspiration."(Joseph Fielding Smith, DOCTRINES OF SALVATION, vol.1, p.186 (1954). 4 ibid., p.243.)
And according to Bruce R. McConkie, scripture is not only limited to what the apostles and prophets say:
"Prophets who speak by the power of the Holy Ghost speak the word of Christ. Every elder in the Church, as he is moved upon by the Holy Ghost, gives forth words that are scripture and they are just as true and just as binding in their central truthful import as any words ever uttered by any prophet. We may not segregate them out, and vote on them, and decide that we, formally and officially, will be bound by them in our conduct. But they are scripture, and they are the voice and word of the Lord. This is what is involved in the sermons of the Prophet. The Father and the Son and the Holy Ghost are one, no matter which one of them says something; it is always the same word. If a man says by inspiration what they would have said, it is scripture."(Bruce R. McConkie, “This Generation Shall Have My Word through You,” Ensign, June 1980, 54)
Of course not just any elder in the church can receive revelation and issue statements binding for the whole church; that is reserved for the prophet. But in a broader sense of the word, anything someone says as moved upon by the Holy Ghost can be considered scripture for himself or for those whom he has stewardship over.