I'm probably going to be the only woman to reply to this thread, but whatever.
I think m/m is my favorite kind of tickling, even if all I can do is watch. It doesn't always have that sexual undertone that most or all f/f videos have.
Tickling, to me, mostly, anyway, isn't necessarily sexual as it is a way to be able to assert a dominance, not a sexual one (depends on the peoples onvolved) over someone, so when I see two guy engaging in such an activity, it's exciting, in a Christmas morning kind of way? I'm sorry if that doesn't make sense or I explained that weirdly, my bad.