As long as it is up long enough to be taken into evidence as a case, it doesn't matter. Even if it isn't up on the web, if there is knowledge of its existence it can be used in a case, copyright or not.
I think the bigger concern is that they play music to drown out the audio but any action which was recorded would still be available.
Legally, I think it is a minor speed bump but not one that I think will catch on or put a crimp in citizens recording unlawful police activity.