how do I get a Quicktime video window to play on an external monitor, simultaneously using the laptop for something else?

Question

Using Macbook using OS-X 10.5.8, how do I get a Quicktime video window to play on an external monitor, simultaneously using the laptop for something else?

I have a Macbook circa 2008 which has OS-x 10.5.8. I recently installed an HDTV in order to watch videos from the Macbook on a larger screen, while continuing to use the laptop for other things. I am unable to play a video on the larger screen unless in the mirror arrangement of the screens. With a side-by-side arrangement, I can drag the folder which contains the movie, but when I click on open, it opens and plays on the Macbook instead of on the tv. Other folders also open in the laptop window, not the tv.

http://uk.answers.yahoo.com/question/index?qid=20080914024038AA5ivCZ

This suggestion of dragging the window doesn't work.