I lasted a few minutes but had to stop watching.
Yes, the points the people were making are true regarding Joel Osteen and what he teaches. (I didn't watch too much of the video, so I don't know if they went on an attack of everyone).
How they do it, however, could be refined. The whole megaphone approach to shouting at people turns people off.
There are better ways to try to open the eyes of believers so they can depart from teachers who teach error or hold back part of the counsel of God.