I have read that the word used in reference to David dancing before the Lord means basically leaping excitedly - not like what we would call dancing today. Plus, it was just him - not the whole congregation dancing at once.

There are several places in Israel's history where they celebrated their victories with dance - but I would not necessarily call those times of worship, but rather of public celebration - and again it was not the whole congregation of Israel dancing at one time or together. In Exodus 15, we see Miriam and some of the women dancing.

Exodus 15:20 And Miriam the prophetess, the sister of Aaron, took a timbrel in her hand; and all the women went out after her with timbrels and with dances.

I do not believe Ecclesiastes is referring to any kind of dance used in worship - but like what happened above, some kind of vistory/celebration dance. From what I recall of Israel's history, the men and women worshipped separately, and would have also danced separately - not like some public dance where the men and women are together and have their hands on one another, moving suggestively. If a husband and wife want to do that privately in their home or bedroom, that is up to them - but it has no place in the public life of the church or of a Christian.