on this Dell, compared to running the mplayer binary from command line, there is NO comparison, SMplayer wins hands down. Mplayer from the binary, even with the luddites arguements added still struggled to play 360p fullscreen, and used 98-100% CPU. Compare that too SMplayer using 50-64% CPU streaming 720p and 76% playing back 1080p.
I can still do the ol copy and paste the url of the video in Firefox and paste it into SMplayer and stream 90% HD web content that way. It almost streams 1080p, I bet if I added some arguments (you can actually do that in the player but I haven't tried yet) it will. I also haven't tried some of the other codecs yet, there's a least a hundred or more to choose from.
I think there is something magical in that ppa:rvm/smplayer's codecs. I read a comment on the Ubuntu forums from someone who said Smplayer had come along way, and on his machine beat Coreplayer. That got me interested. I will be getting another Power Mac soon (I hope) and will try this out in Lubuntu on it. I am also not an expert at compiling in OS X, that is something I need to learn more about. It isn't that difficult in Linux.