I don't know if this has been thought of before, it probably has though:
I know Venom has not been "officially" confirmed yet by sony. And we have seen that the spidey shot in cleveland was wearing a red suit. So now assuming there will be venom in this movie, there are a few possabilities I can think of:
1. The cleveland shooting will be used for earlier footage in the movie before spidey gets the black out fit.
2. The black outfit is spiderman, just in a different color costume (or symbiote)
Or, this one I think perhaps:
It is the symbiote, but not spiderman. The person in the teaser photo of spiderman in the rain is actually venom himself, played by Topher. Perhaps the symbiote or eddie becomes jealous or spiderman, or wants to become like spiderman, and changes to take on the apperance of the spider. Mabye he uses this to get at spiderman, and to get the people jealous at spidey, or perhaps even get mary jane upset at him. Just my thoughts, please don't poke fun at me if someone already thought of this, I haven't been here long and have not taken the time to read every single post.