Is it possible to film a character doing something, thn remove him from the clip, to look like it was done by a ghost?

uhh, yeah, it's totally possible. It will require some medium to heavy duty compositing (and possibly CG).

Could you describe the shot more indepthly? And does the camera tilt, pan, or do any other movement? ...that'll make it much harder.

more info please

if possible fishing line would be a better idea. You need to explain what you are trying to achieve further.

There was a making of the video for a new Cure video. The song sucks for the record - they went down the tubes it seems. But i digress...anyway, in the video they did exactly what you are talking about for large objects, like chairs in mid air and the sort, coffee cups moving off the saucer etc etc. And this was accomplished by using actors in complete head to toe vibrant greenscreen suits and obviously a full load of professional lighting. Then, with some serious keying, they took them out in post. All of the shots were stationary to provide the background fill.

Sorry for not giving more info guys. Most of the shots WILL be done using fishing line, but this particular shot includes a kitchen cabinet being opened and glasses being thrown by the 'ghost'. This can obviously not be done with fishing line, and yes, the shot will be stationary.

actually i think the cabinet opening could be done with fishing line, tie to the handle. The glasses are to be removed from the cabinet and thrown? is that correct? It's not going to be an easy shot, i have an idea though. Have you seen those gripping arms that are sold for old people to reach high places? Buy one of those (like 10-20 bucks i think) and paint it the most vibrant green you can find. Light very well to get an even green tone on the arm, and then use a combination of cropping or track mattes, then use chroma key to remove the excess. Worth a shot and relatively cheap.

EDIT: heres an example of one, i believe the one i originally saw on tv was a little less bulky than this.

http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=4006970&storeId=6970&langId=-1&productId=433445&cm_ven=TL&cm_pla=DF&cm_ite=shop

good idea Jeff. word.

One issue I see you might have is the reflective and transparent nature of glass. It'll make keying or otherwise matting out the 'ghost' actor/apparatus very difficult. It might be better to use a less noticeable color support (so any reflections look natural) and rotoscope/matte out the shot by hand.

Have you storyboarded your shot/s? Do you want to do it in a master or do multiple close-ups? Depending on how you shoot it, the way you do the effect will change. I renew my suggestion that you just composite a 2d picture of a glass (with a good transparency matte) onto a BG plate shot. This could work great in the master. Also, rather than clamping the glass, what if you just put it on a thin platform (think waiter's tray). Then, just shoot the glass at a very slight high angle so the platform doesn't cover the glass (either infront or behind). Then you could use rough garbage mattes (or even a key if you really want) to get rid of the tray and the person holding it.

Again, if you can get more specific on your shot, it'll help. Maybe even post 'boards in our new 'photo album' feature here at SF?

Photo album?

Yep, photo album

Whoa... slow down... If you are going the CG route, why would you take the harder method of keying the actor out instead of compositing the glassware in?