I don‘t know what you mean by indicating URL A or B as dynamic. Do you really care about specific pages?
If not - following gives you all visits where the user visited at least 2 different sites:
“visit“ segment with condition „visit depth is greater than 1“
(see here about what increases visit depth: Hit Depth )
But be careful: the segment will not look at any segments you have applied to filter your data! that means, it also includes visits that had 1 page view outside of a desired website-section and only one within since visit depth is equal on all hits within a visit (in this case at least 2 and thus matching your segment definition)
another solution might be to create a „visit“-segment where you exclude
a) all visits with „page views“ = 1
b) all visits with „page views“ = 2 and „reload“ does not exist
havent tested this idea and don‘t know if you can use „reloads“ in a segment...