I just found this, he explains it very well for a layman.

One issue, where he talks about video recording police and cites § 21.15, Tex. Pen. Code, that’s not really valid. That section deals with improper photography for sexual gratification, in other words for those pervs who plant cameras in restrooms, etc. Second, that section was struck down as unconstitutional, see Ex parte Thompson, 442 S.W.3d 325 (Tex. Crim. App. 2014); but see Prosecution of the Offense of Invasive Visual Recording, 2015 Tex. Sess. Law Serv. Ch. 955 (S.B. 1317) (Vernon’s) (new version of the law, narrowed, but unlikely to survive strict scrutiny).

Instead, base your filming of the police on the First Amendment and general case law.

In any event, this is a good explanation of the Fail to ID law in Texas.