Most wouldn't notice such subtle sexism, but it's still worth fending off the appearance of it.
I wouldn't change this video (except that including a female face among the "well known naturalists" is a good idea if possible); I'd create an additional one aimed at contrasting the fair treatment and respect women can expect from naturalist thinkers as opposed to naive-traditional or ideological-religious ones.
As for your first suggestion, although I don't know what it feels like to be introduced to "naturalism", I think it's a mistake to lead with maximum rigor. The level of difficulty seemed appropriate to me.
As I saw it, the purpose of this video was to suggest that naturalists might be nice, happy, cool people, as opposed to, say, baby eaters - to motivate people to actually entertain the site's writings.
I've just launched WorldviewNaturalism.com, which is intended as a simple "landing page" to be used for introducing your friends to scientific naturalism. Many of the recommended readings linked there are written by LWers. Enjoy.
(This is a very old personal project on which I've spent a few hours per month, and it is not at all associated with the Singularity Institute or the Center for Applied Rationality.)