1.) They're either storyboard sketches, and the F4 and DD name drops are to show that the SM movie universe coexists with these.
or
2.) They're fan-made. Good, but fan made.
I do like, however, the idea that Harry's shitty costume is just a test suit, as evidenced by Spidey beating the crap out of the Green Goblin (normal movie costume) and Sandman.
Just click it. You know you want to.
http://filmick.blogspot.com/2006/06/spider-man-3-teaser-trailer.html