So the question is how to configure Frontrow to display those HD trailer. Well after some searching in the setting it appears there's no easy way to choose the quality of the trailer. After some rummaging around, here's the solution.
Open a terminal and type the following command
defaults write com.apple.frontrow EnableHDMovieTrailers -boolean true && killall "Front Row"Now reopen Frontrow, go to the Trailer menu. There’s now a HD Trailer at the top of the list.
Voila ;)
Enjoy.