I think that in general men and women's brains work very differently with regards to physical attraction. I believe that man utilizes their sense of sight more than their other senses when it comes to attraction while women access the other senses more and visual stimuli is not as important for them. I realize that my next statement is a generalization but I have certainly noticed many more occurrences of unattractive to average men with beautiful girlfriends than I have seen unattractive to average women with very attractive men.
I am 38 years old and I have been single for 36 of those years so I have seen my fair share of adult videos and I would have to say that lesbian videos would definitely be my preference but I've never had any particularly strong desire to be with multiple women. For me it is more just that watching a sexual act is more fulfilling when both of parties involved are physically attractive to me. I think that when god, mother earth, evolution or whatever you believe in chose to create the two genders they went for curves and grace and elegance when they built women. When it came to guys they went for, "the last chicken in the shop" look. Personally I am glad that women aren't as visual as guys because I cannot see what any woman would want from us.