Do bodyfeeder weapons work against undead?

[brian14]

Or constructs?

By "work", I mean do you gain hit points when you score a crit?

[testing1234]

yes.
all critical effects are independent of a monsters crit immunity.
maiming holy burst smiting ... and so on all work on critical immune monsters.

[Rodrak]

Or constructs?

By "work", I mean do you gain hit points when you score a crit?

Yes. You don't get a critical hit of course, but the bodyfeeder effect will proc and you'll get extra temporary hp.