Another opinion from the straight-ish perspective.
Yeah, sex is sex. Gay sex is a sexy behavior, and men in general are wired to get turned on by just about anything. They'll see the erections, they'll see the sensitive bits being touched -- and I guarantee you that they'll get an arousal response. "It" will move. And I'm confident that if you sneak a gay video onto a straight guy's computer, and he "accidentally" clicks on it, he'll watch it enough to get a hardon.
However, getting the average straight guy to admit that he'd so much as glance a video -- good luck with that. There's a social stigma with being labeled something you think you're not when you watch certain acts, or even experimenting. If you sit him down in an environment where he's allowed to have an open mind without threatening his sexuality, then you'd be surprised.
Now with all that said, while I firmly believe that straight guys can get aroused watching a degree of gay porn, they will not actively seek it out or use it for their primary masturbatory material. The guys who say they're straight, but ultimately fall back on gay porn, is a bit of a conundrum. There's a level of curiosity there that draws him away from being "perfectly straight" -- but I'm not going to belabor on labels here.
So my bottom line: yes, even straight guys can get turned on by gay porn. But they're not going to actively look for it, or necessarily watch it long enough to masturbate to it.
My personal tolerance of gay videos -- I can sit through jack-off sessions, and even some fellatio. But penetration and passionate kissing; not my thing at all.