iTunes is a good music player, but its video playing features are a bit clumsy. This script allows you to play the video files with mplayer. Save it to ~/Library/iTunes/Scripts/, choose a video file in iTunes and then select this script from the scripts menu.
property apppath : path to application "MPlayer OSX"
tell application "iTunes"
repeat with x in selection
set thetrack to location of x
set played count of x to (played count of x) + 1
set played date of x to current date
with timeout of 10800 seconds
tell me to do shell script quoted form of POSIX path of apppath & "Contents/Resources/External_Binaries/mplayer.app/Contents/MacOS/mplayer -fs " & quoted form of POSIX path of thetrack
end timeout
end repeat
end tell