The person who stole JUSTIN BIEBER'S computer and camera has posted some of his private videos online.

--This person goes by the Twitter handle @gexwy . . . and he or she posted two short clips on a YouTube account under the same name.  (--You can watch them here.)

--Neither one is very scandalous.  One has Justin pranking a friend backstage by dumping some kind of powder on him. 

--The other was taken several years ago, because Justin is a lot younger in it.  It just shows him in a room with screaming girls looking in the windows.

--However . . . "Gexwy" also sent a five-second clip to PerezHilton.com that shows Justin at a pool party.

--Supposedly, there's more to this clip that will be revealed later today, and it's something Justin wouldn't want anyone to see.  (--Here's the clip.)

--This must be legit, because Justin is now FOLLOWING this person on Twitter.  And yes, it really IS Justin.  They exchanged a few direct messages . . . plus some public messages in which the culprit does promise to release footage today.

--He . . . or she . . . said, quote, "TOMORROW PUNK!"

--And Justin had this to say . . . quote, "No matter what you have and what you post tomorrow I know my fans won't leave me.  Screw it.  #toostrong"