the gtx550ti is a 1gb card.... why are you complaining about needing 256mb?
you should be able to play bluerays perfectly fine even without a video card. integrated on cpu works perfectly fine. they fixed the whole issue back when nvidia was still providing on motherboard IGP solutions in 2009ish.
the roku and blueray players can do it because they have similar graphics processing either on chip or on the board.
http
/www.mycablealternatives.com/2011/07/roku-2-xs-teardown/