You mean when Danaerys meets them in the house of the Undying?
I've seen it too, and I was kind of (slightly) disappointed. A little bit because of the missing dragon-like features (Ok, *my* interpretation is that they are from Danaerys' dragon blood, but probably GRR Martin didn't mean so), then because in Danaerys' vision Rhaego is blond, with purple eyes, and has copper skin. So he should look like *both* parents, and not only like a Dothraki.
(well, it's not such an important detail, indeed
)