97 votesAlexander commented
If I add the script presumably you know the paths visited for each visitor. So you'd have data along these lines stored:
# user_id: 123
# cookie_id: 456
# paths: ["/contact", "/product-a", "/checkout"]
My guess is such data would enable me to retroactively (after 123 visited my site) add a list with everyone who visited "/product-a" and that 123 would then be included in this list.
Hope this clear things up. There may be other aspects playing into this, for example you seem to be setting cookies on other domains than your own, which may or may not affect whether this is possible.