It's in the context of the previous comments, "X person robbing Y person". I didn't want to be redundant. No matter what crimes are happening, there are no police involved, so there is no police transparency motive to release the video.

The motive is to provide the public with information. Some of this information may be useful to identify the (gang of) attackers.

That's a perfectly fine motive, but it's not enough to force anyone that has such a video to release it completely publicly. And BART in this case is basically an "anyone". They have no particular involvement.