Hi, This is just for the interest of the guys who replied to my posts about ghost in the jar or anyone else.
This is a rough mockup, but basically I did what you guys told me and duplicated the background, then masked the duplicated layer so that it was only the jar. I put the mist emitter and video layer between the jar and the background. THen duplicated the mask i used for the jar, and put it over the emitter and video. I messed around with blend modes until it all looked right.
To me, this looks like its inside the jar pretty much.
Oh and to solve the problem of the mist moving to one side when i moved the jar from right to left, i finally worked out that you just go into the particle emitter values and change "Attach to emitter" up to 100%. Simple.