New high quality footage of WTC7 burning

I found these clips in the 9/11 archive that was published by archive.org. These videos were taken from the high quality MPEGs that were available for download for some time. Links are provided to high quality copies of this footage as well as links to the streaming versions on archive.org

Showing the South side of WTC7, broadcasted by NBC at 1:45 PM.

video

high quality XVID (640x480 de-interlaced) :
http://www.megaupload.com/?d=CV4PU0IQ

link to archive.org (@ 22 minutes):
http://www.archive.org/details/abc200109111323-1404

What is that black marking? It looks like a hole, but it seems much too smooth for being caused by falling debris. It looks to be at least 15 stories high.