At a Chassidishe Wedding, there is a special dance done, known as the Mitzvah Tanz. Where is the source for this dance and what is the meaning behind it? Also, why is it not done at Litvish Weddings? Here is a video of the dance for reference: http://www.youtube.com/watch?v=YcE0dUAMcBw
One source is the Machzor Vitri chelek 2:496 (talmid of Rashi) at the end(last line). The custom brought was that the chosson and kallah would be danced around.It is not exactly like the mitzva tantz of today which is solely focused on the kallah.