When I select "Choose Program" it gives me an error

http://datboiwilly.resentment.org/chooseprogram.jpg

Before you assume, the file is ALREADY associated with quicktime and if I double click it then it opens up just fine...but my point is that I want to have it so that whenever I right mouse click any type of file, I can always do the choose program option to open up a file ith something else. If I click on "choose program" then it just gives me that error and the file that it refers to is the one listed inside the quotation marks. I hope that makes sense, please help. I downloaded a program called MagicTweak and one of the options was so that it opened up any unassociated file with notepad when I click on "choose program". I didn't realize that was an option I selected so now I'm trying to reverse it...