I did find this quad story too far out to be believable.
That's because you have a brain.
And sure, you all look alike, won a free trip and brought your orange polos to Vegas!
I figure the three wore the same shirt to make things more confusing for the police. I'm not sure I understand all the details. For instance, when CSI found the first orange-shirted guy, he was hiding in the closet. Why? And why was his friend covering for him? I think that this orange-shirt brother said something about a bar fight, so was that supposed to be why he was hiding?
Also, I was positive that this guy and the shooter did not look exactly alike. I thought their eyebrows were quite different, and I was puzzled why no one else saw the difference. But I guess my eyes were just playing tricks.
So did one of the other quads film the suicide video? Didn't seem like the dead quad was too interested in playing that role.
I think in the flashback with the young brother in the room, you see one of the older brothers sitting in a chair as if he'd just recorded the video.
I thought the young brother looked like David Mitchell
The nightclub where Sarah pulled her gun looked familiar. I thought it was used in another ep. If so, that shouldn't be a surprise. They've probably used lots of locations more than once.