I call it DC voltage because it is, it's simply pulsating DC, but there is no negative going part of the waveform. It's not filtered DC, just raw rectified DC. If you stick a single diode rectifier in series with the AC and your load, you get DC. It's quite possible to generate DC using a triac and an AC input voltage, the smoke output can generate either positive or negative DC outputs, depending on programming.
The power in to the smoke triac appears to be direct from the track voltage, as the output of the smoke pin during boost is basically the track voltage minus the drop across the triac. That's also why there is a little glitch at the zero crossing. The normal half-wave output very close to the amplitude of the positive side of the track voltage input.
I didn't think to have two channels and show the track voltage next to the triac output, it would have been a good illustration.
