TV USB power is usually very dirty, as well as limited to 2.5W. A huge electrolytic capacitor between 5v and ground might solve the problem for a Pi Zero, but I used a Pi 2 and an external power supply.
Discussion
I imagine TV USB power is really unstable for something like this too - just less convenient because of +1 more outlet to engineer. That was my concern of TV USB power being 2.5w and generally underpowered/unstable. Might have to play around with that aspect - external power will probably be the more sensible solution, just more hassle lol.