According to primatologists George Schaller and Esteban Sarmiento, the smaller figure is an ape, and must either be: 1) an exceptionally large gibbon, or 2) a year-old chimpanzee, or 3) an unclassified ape species. Gibbons and chimps are commonly called "monkeys" but are technically apes.
Reasonable skeptics are left with the possibility that the footage shows
a lurking human releasing an ape into the trees -- an unlikely scenario considering
that very few people own pet apes ... and if you were to release a pet ape into
the trees you would not get it back very easily ...
Based on measurements of the tree taken at the site, the swinging figure is
approximately 3-4 feet tall from head to toe -- about the size of the figure
in the Jacobs photo from Pennsylvania. - Source: http://www.bfro.net/news/nybaby.asp