Plex says this about their commercial removing tech:
"The process is CPU-intensive and can take several minutes to complete, depending on the recording duration. On a reasonably fast CPU, we typically see a 30-minute recording take 2-4 minutes to process."
Assuming they know what they are doing, real time blocking seems not possible with a reasonably modern approach.
"The recording is analyzed on various characteristics such as black frames, silences and changes in aspect ratio.
Based on this information Comskip segments the recording in blocks and using heuristics, together with additional information such as the presence of logo, the scene change rate, Close Captioning information and other information sources Comskip tries to determine what blocks of the recording are to be characterized as commercials."
It doesn't say it explicitly, but based on this and the note on high CPU utilization, I get the impression it has to look back and forward to determine where the commercial is.
Given enough of a buffer and a historical corpus, it should be possible to do this in near-realtime, but likely with a few minutes of buffer. Especially with some kind of historical trained classifier, it should be possible to do this in close-enough-to-realtime-to-be-useful scale.
"The process is CPU-intensive and can take several minutes to complete, depending on the recording duration. On a reasonably fast CPU, we typically see a 30-minute recording take 2-4 minutes to process."
Assuming they know what they are doing, real time blocking seems not possible with a reasonably modern approach.