I'm not aware of such a feature, though it would certainly be nice. Since Vegas already has the waveform monitor function, it obviously could implement something like this. For efficient use it would probably have to precalculate an "average video level" for each clip much like the audio waveform preview is done now (.sfk file). That process might take a long time, because it would have to render every frame of the entire video.
Edit: well, if you only care about 0,0,0 black level, you could add the optimization that rendering of any frame halts as soon as a non-zero pixel renders. That would speed it up a lot.
Vegas does not provide any features that make any decisions based on either the video itself, or on the information (e.g., date/time) embedded in the file.
If you know AVISynth, I have written AVISynth scripts that do blank frame detection and also scene detection, and then output a file that can be imported into Vegas as markers. You can then use a Vegas script to cut your video at these marker points. Not exactly straightforward, but it sure makes quick work of rough-cut editing based on content.
Not exactly what you're looking for but you may find VASST's Ultimate S "audit" function to be helpful. It has saved many a re-rendering effort for me. Launching "Audit" places a maker at gap in the video which of course would appear as black when previewing/rendering. You can set the minimum length of gaps to be found.
But as far as I know, "Audit" does not detect black video.