You were actually in DC during that video on DC 295 and had just crossed the boundary from Maryland to DC when you saw the MRCD. By law, Maryland is only allowed to use speed cameras in construction zones and all of the units I have seen are truck-based. DC has no such restrictions and sets up those portable units wherever they want
EDIT: Maryland is also allowed to put speed cameras in school zones, but they are limited to 0600-1800 active time
THIS is an awesome piece of research for Chicago........... it appears that we in the U.S. will be fighting these new menaces until adequate databases for at least the 5-8 major cities are compiled........
Those are MRCT cameras, same units in Chicago and NYC. I did testing on them with the Pro M and included a good bit of info on them. That post is in the testing section.
If anyone in the US is running a Pro M or RC-M I recommend using MRCT and MRCD narrow with MR Filter on High. That will pick up these MRCT cameras without issue while giving you the best filtering performance. Cameras will be detected as MRCT, but MRCD needs to be on as well.
I did a road trip from Denver to St Louis and was in Monroe County IL south of St Louis. They had speed signs in school zones and my R3 did not make a single sound at any of them but they were working and displaying your speed accurately. Not sure if this is part of the MRCD/MRCT.