Who was right? (Roomate squabble)

So I need a 3rd party opinion about something just happened between me and my room-mate, and I hope Reddit can help me come to a decision. I am attempting to make it seem as impartial as possible without giving away which party is which.

Party A is using his desktop while Party B is playing a handheld next to him. Party A and B wish to watch a video both enjoy. Party A also wants to play a game on his computer. Party A flips a coin and decides to watch the video.

After watching the videos and wanting to go to sleep Party A goes to shut down his computer, while Party B says " So I can't watch the video on your computer, while I play on my computer?"

Party A says "You had a perfectly good laptop we could have both watched it on while playing our respective games."

Who do you think was in the right?

Details.

Party A. -Willingly flipped a coin. -Made no mention of Party B's laptop until after the first 2 videos.

Party B. -Routinely suggests use of Party A's monitor for both parties viewing it has become the "default" -Doesn't like use of his laptop by 3rd parties without permission

tl;Dr, People bitching about stuff that doesn't matter.