I am familiar with this location. The Department of Education is a very large building. The main entrance is on Maryland Avenue, whereupon visitors must pass through security, sign in and get a visitors pass. The doors in the video are on C Street, on the rear side on the building.
An "All Access" entrance is what used to be called a "Handicapped Entrance" until the word handicapped fell out of favor and the signage was changed. This would be an additional access point for those with special needs, particularly at older or historical buildings where the main entrance can't be retrofitted to comply with ADA. These locations are often unstaffed and locked, with an intercom to request access.
The Members choice to tug on the doors of a handicapped entrance, en masse, rather than go to the main entrance (generally unlocked, but with a lobby and security checkpoint) seems a bit theatrical and detracts from their message.
This is one of the most disturbing things I have seen Trump do so far. Even if the evidence against these men was overwhelming (and it certainly is not) the idea of "deporting" them to a prison in a country they didn't even come from is beyond the pale.