In my humble option I think that the logo need not be changed just because of video sub-forum is set up. Because the word photography does not refer only to still picture.
The noun photography has 3 meanings:
Meaning #1: the act of taking and printing photographs
Synonym: picture taking
Meaning #2: the process of producing images of objects on photosensitive surfaces
Meaning #3: the occupation of taking and printing photographs or making movies
Video can also be considered as photography too. The definition does not specifically defined photography as a still image. Actually video is form by many still image taken at a very high speed ranging from 25 to 30 fps (may be even more).
However, I have no objection for the changes of the logo.