I'd like to try as best I can to address why I believe the audience responded that way.
You have to look at two aspects here:
1. the make-up of the audience.
2. the history of racial injustice, unequality and brutality inflected upon African-Americans during a long period leading up to the time inwhich the incident Mrs. Sherrod spoke of took place.
Most of the NAACP audience (naturally) were African-Americans, but they were older African-Americans, people who saw and/or experienced the cruelty of racism first hand. To them, hearing that one of their own who wielding such power over a White man who was in the same boat as other Black farmers of the time, struggling just as they were, was viewed as vindication. To them, it was like "Finally, the White man knows what we're going through. Finally, the White man gets a dose of his own medicine. Finally, the White man feels the injustice WE have suffered for generations." To those older African-Americans in attendence, hearing Mrs. Sherrod admit that she didn't put forth her best efforts to help a White farmer who was struggling just a hard as a Black farmer to keep his land but was being denied the assistance he rightfully deserved under the law was justice in their eyes, justice that had been a long time coming.
You have to see things as they saw them from their generational perspective. Put another way, it's like how many African-American's felt when Medger Ever's killer was finally found guilty of murder some 40+ years later. Finally, justice was served.
Now, I'm not saying that the audience's actions were right. But I am saying that as a Black man who HAS experienced racism before and who has studied African-American history and reviewed some of the injustices that have taken place against my people, I can certainly understand their reaction. Inappropriate as it may have been, I can understand it. I'm sure that if a generation of Whites had experienced the same type of racial injustice, unequality and cruelties, many of them likely would have responded the same way. As for myself, I watched the video but did not respond in the same way as those in attendence as I listened to what Mrs. Sherrod's speech. My approach was far more laid back. Perhaps because the scares of racism don't run as deep for me as they apparently did for some who were there...and likely still do to this day. Still, I can't say I blame those who applauded for their reaction. When you've been hurt and mistreated so bad for so long and you hear perhaps for the first time that someone you identify as "the enemy" and you know those of his kind were receiving better treatment than yourself and both of you were in the exact same situation, I don't think anyone can blame them for their reaction.
