Amber Rose's Sexy 'Mask Off' Video with Future Cool with Blac Chyna

Amber Rose and Blac Chyna are still BFFs ... despite Amber crawling into the lap of, and licking the face of, Chyna's ex-bf, Future.

Amber is the lead chick in the rapper's "Mask Off" vid -- hot stuff that required them to get REALLY close. Considering BC and Future had a nasty breakup about 18 months back ... you'd think the sexy scenes might rub Amber's pal the wrong way.

But if there's one thing Chyna understands, it's money -- and she knows that's why Amber shot the video, not to take a shot at her. We're told Future's team reached out to get Amber for the role, and with 'Mask' being the hottest track out now ... she couldn't turn it down.

Our sources say BC's got her hands full right now with Rob Kardashian and baby Dream ... so, she's not sweatin' Future.

Besides, tattoo removal would be her more pressing issue.