QuickTime X Applescript
tell application "QuickTime Player"
    set movieName to the name of the front document
    set savePath to a reference to POSIX file ¬
        ("/Users/WBTVPOST/Desktop/" &amp; movieName &amp; ".mov")
    export the front document in savePath using settings preset "720p"
end tell


System info: AppleScript version: 2.7  System version: 10.13.6

PS.  User @wowfunhappy is absolutely correct in saying that the export command does re-encode a file.  It has to in order to apply whatever settings are contained within the preset.