I believe Charlotte-Mecklenburg Police Chief Kerr Putney did the right thing in holding back for a time on releasing video footage of the shooting, that is, supposing the reason was that witnesses were yet to be interviewed.
Had the witnesses not first been interviewed, their testimonies of what they saw might have been tainted by saw in the video. You want their testimonies to be of what they saw, what they witnessed, no more.
Once their testimonies were on file, then the video could be released. I don't know waiting for the witnesses to be released is why the video footage was not released early, but I suppose that the reason.