By 'launching movies' are you referring to launching them from LW or from your desktop? VLC is reasonably reliable to open anything that QT can't open. Personally I open files from within VLC. You may have received a QT message because QT lacks the appropriate codecs to play the media. QT Player ain't what it used to be.

I forgot to mention, 'if' you want iTunes to open the files after downlding, set it in your LW Prefs. iTunes will then copy these files to its own library. Check that it does this.

(Keep your water usage to a minimum - a drought message, perhaps I should migrate to Syd.- it's freezing here! Just a local joke!)