In response to the second video, about the facehuggers -
Personally I have always preferred the idea that whatever the Hugger was inserting into the host was more along the lines of a "renaissance semen." Utilizing host DNA to finalize the early stage of gestation. This would also potentially allow the injected material to pass through the esophageal wall and attach near the heart and lungs. It would explain the very adaptable and dynamic nature of the Alien appearances and cross breeds, and just how nastily the genetic material of Ripley seemed to fuse with the Alien in Resurrection. It's amorphous and subversive.
Also, Hicks, you guys are doing a wonderful job on these videos. Very entertaining, atmospheric, and informative. Very high quality audio, as well.