Try examining the package contents of the DVD player (control-click the app and select "Show Package Contents"), and navigating into the Contents/Resources folder. Now Show Info on the application itself, and remove some languages. You'll see the ".lproj" folders disappearing from the Resources folder. If you simply uncheck the checkbox, you'll disable the language without deleting it; this moves the .lproj directories into a "Resources Disabled" directory - how very Classic ;-)
I can only presume that moving them speeds up launch time whilst allowing them to be recovered again if necessary.
As always, apologies if this is old news.
[Editor's note: I'm not sure when this was added! I'd certainly never noticed it before reading this hint. Who knows, maybe it's been there since the Public Beta, but surely someone would have sent this in by now. Anyone have any idea when this feature was added? A quick caution -- even though the "Remove" button has three dots, usually denoting a follow-on dialog box, its action is instantaneous. Luckily, the Finder's undo command saved my deletion of English from the DVD Player!]

