Hmmm. I suppose you can try the QuickTime Player 7 download and let it install the plug-ins it offers. Barring that, the next best thing to do is get Firefox and use it to go to the trailers page. Look up the trailer you want and click on it and see what, if any, data information you get in the 'page info' tool.
In the Firefox, it is the bottom item in the Tools menu.
IF you see a line that looks like this: http://home.comcast.net/~foodandart/MacForums/FirefoxInfoTool.jpg - where it is in the Media Info window and it is embedded - there is the address for the video. Highlight to the end of the ".mov" and copy (like I did)
It will play *into* a QuickTime player, so you go to that, and use the QT menu to select the Open Location..
http://home.comcast.net/~foodandart/MacForums/QTOpenURL.jpg and..
Paste into the address bar: http://home.comcast.net/~foodandart/MacForums/QTOpenURLBar.jpg - hit Open and it SHOULD load into a QT player window.
In the picture you can see that I changed the resoultion to the 1080p and yep, that loaded. Whichever tech at Apple is using the naming convention is fairly predictable so that you can try with any trailer and put in the "movietitle-tlr1_480p.mov" or "movietitle-tlr2_720p.mov" to find different trailer versions and sizes. Look at the URL with the Firefox Page Info Tool and you get the studio name, then the film, then the film trailer version and the filesize.
As long as you open with the player, it should then save.
With the regular QTX you'll have the budget "iThing" filetype Export/Save option: http://home.comcast.net/~foodandart/MacForums/SaveFilmClip.jpg
And with QT7 with the Pro Key you get the full monty of Export/Save option:
http://home.comcast.net/~foodandart/MacForums/QT7ProSave.jpg
I'm not sure that your Firefox info tool will work, since your plug-ins seem to be flown, but the page may pull up that info anyways.
Can't hurt to look and let me know what you find.
Good luck!
Deb.