User blog comment:Astarothfan/High School DxD BorN episode 6 review/@comment-26322543-20150510003334

Considering they produced a tokusatsu show in less then a month, I don't think it's that surprising they made those videos with based on Azazel's descriptions. The fight against Kokabiel was observed by Vali, who was his underling by then and would have reported to him, and Tannin witnessed the fight against Kuroka, so he could have asked it for him. Of course TNK re-used the footage completely for obvious reasons, but it's not impossible to think something similar could be manufactured if they can make realistic faces with CGI.