When we use mixed html and flash content, we usually face the problem of overlapping flash contents over html text. In the case of mere html we use z-index to format which content should be on top. But Z-index cannot do nothing here. So the recommended option is wmode parameter. Sometimes the wmode mode also does not help us to avoid this overlapping problem. This is because sometimes we forgot to add wmode in two places. We need to add wmode = transparent or opaque in both flash var and in embedded tag parameter like this:

A detailed description can be found from the makers :