In watching the videos, it appears to me that once the officers made visual and verbal contact with the adults in the home, all claims to exigent circumstances justifying warrantless entry fall by the wayside. I see no immediate risk to the lives of anyone inside the home, and they certainly had time to obtain a warrant.
I think what we're seeing is the officers in this case believed that a DV call necessitates entry into the house regardless of any other circumstances they might encounter at the scene.
And yeah - tasering the woman appears to have been done without any sort of justification whatsoever. You can't taser people just to shut them up.