[MacDV] QT software?

[* L a n n y C o t l e r]

I download an QT .avi file. But when I go to play it, I get an alert 
saying "Some necessary QT software is missing. It may be available on 
the QT web site. ...Click the Continue Button to check for this 
software.

What software am I missing? The Alert doesn't say. When I go to the 
Apple QT plug-in URL, I get a long list of software to download. How 
do I know which I am missing?

This is the URL I am sent to:

http://www.apple.com/quicktime/resources/components.html

Any suggestions?

TIA,

Lanny