What is this...

Almost looks like a digital flasher

Complementary pair common emitter amplifier. Like in common emitter collector is an output and transistors works as "active load colector resistance" to each other increaing linearity and power use. Instead of traditional common emiter with resistor, a version with active load is a high power output capble maintain at the same time current source characteristic of collector and high voltae gain. Active load works by such way that when one transistor is closing other acting as load open almost to zero ohm so full power can be transfered. And opositely when it open and by such forcing voltage down by taking all curents on herself shorting them to ground activeload increase resistance very rapidly limiting currents conduced to ground saving power . This is if load is drived in paralel like in single transistor version. For load coupled in series oposite situation must be held when one trannie opens active load also decrease resistance make them almost perform short and apply all power to series connected load without limit . I made here 2 audio power amps based on this. Search my circuit list u find them inside easily. This amp freqjently not need preamp cuz it maintain very high voltage gain yet is armed aditionally by current and so on overall high power gain joining driver stage and output stage in one amp. It's weak point is high dependence on HFE changes during operation and this should be wel under controll