A script that literally uses QuickTime to convert videos

qt_convert.applescript

-- commandline `avconvert` didn't want to work and I was desperate, so I wrote this.
-- Use it at your own risk
-- Do what you want with it

tell application "Finder" to set chosenFiles to every file of (choose folder)
repeat with aFile in chosenFiles
	
	-- Change to suit your extension
	if name of aFile ends with ".MPG" then
		
		-- Only do this to MPG files
		tell application "QuickTime Player"
			open aFile
			activate
		end tell
		
		tell application "System Events" to tell process "QuickTime Player"
			
			set frontmost to true
			delay 0.7
			
			-- Export using 720p
			click menu item 2 of menu 1 of menu item "Export" of menu 1 of menu bar item "File" of menu bar 1
			delay 0.7
			
			-- Save with default location
			click button "Save" of sheet 1 of window 1
			delay 0.7
			
			-- Go back to the video window (cos the export progress will open)
			keystroke "`" using command down
			delay 0.7
			
			-- Close the video window
			keystroke "w" using command down
			
			-- You should change this delay to be about the average time you expect a video to take :) 
			delay 27.0
			
		end tell
		
	end if
	
end repeat