Is it true that Tau2 can only output either analog or digital video, but not both?

Both digital and NTSC / PAL analog video are enabled as part of the standard factory configuration for FLIR OEM cameras, including Tau2.

Either or both analog and digital outputs can be turned on or off by way of the Camera Control GUI, or by direct serial command. The serial commands are documented in the Tau2 / Quark Software IDD, 102-PS242-43.