It's quite possible for people to speak at a conference and yet vigorously disagree. Mere participation in a conference together should not be construed as wholehearted embrace of one another's positions. There is a time for everything.
I guess you didn't watch the video as it was long so I don't blame you.
This is a case where group A criticizes and signs statements against group B's teachings and practices and then the next day and in subsequent meetings applauds and shmoozes up to the very ones' they had criticized. With meetings called 'The Mission of God' subtitled 'A Biblical Understanding of Missions' or 'The Shepherd's Conference' or 'The Gospel Coalition' you would expect these are conferences that would invite those with like minded ideas, not a conference debate-slugfest. No this is all scamming for prestige, status and popularity, something our Lord warned us about.
Luke 20:46 KJV
[46] Beware of the scribes, which desire to walk in long robes, and love greetings in the markets, and the highest seats in the synagogues, and the chief rooms at feasts;
Luke 11:43 KJV
[43] Woe unto you, Pharisees! for ye love the uppermost seats in the synagogues, and greetings in the markets.
Matthew 23:5-8 KJV
[5] But all their works they do for to be seen of men: they make broad their phylacteries, and enlarge the borders of their garments, [6] And love the uppermost rooms at feasts, and the chief seats in the synagogues, [7] And greetings in the markets, and to be called of men, Rabbi, Rabbi. [8] But be not ye called Rabbi: for one is your Master, even Christ; and all ye are brethren.