very nice find, and it also coincides with the aircraft discovery from earlier. for those claiming that the bike from GTA:V's trailer has BMX-styled handlebars; it doesn't. the handlebars for the two bikes are exactly the same, OP's picture is just blurry.
here's an enlarged shot of the bike in the GTA:V trailer (the quality is quite bad, but the styling of the handlebars is easily distinguishable). you can see that what was previously being mistaken for an "A" frame was actually the top tube
of the bicycle frame. you can also see the single brake lever on the left side of the handlebars (which is exactly the same as the bike found in MP3), although it's just barely visible:
here is the bike in MP3 (taken from OP's picture):
the coloring of the bikes and the near identical styling of their rear wheels goes without saying, but knowing the people around here, it's best if you mention it anyway.