There are reason to not release it right away, especially if the person who was shot (after opening fire first) was not the subject of the warrant. There could be video that is needed as part of the overall investigation into the person who was the subject of the warranty, and the shooting investigation by the Texas Rangers.
Automatically thinking it is some kind of coverup for police maleficence does not do anyone any good.
The video will be released sooner or later and if it is like most body camera footage, it will show it to be a justified shooting.
"If you will not fight for right when you can easily win without blood shed; if you will not fight when your victory is sure and not too costly; you may come to the moment when you will have to fight with all the odds against you and only a precarious chance of survival. There may even be a worse case. You may have to fight when there is no hope of victory, because it is better to perish than to live as slaves." - Sir Winston Churchill