Yes, all 10 passenger entry doors on the 747-400 main deck are plug-type doors:
The main deck passenger entry doors are used to enter and exit the airplane, and
serve as emergency exits. The ten passenger entry doors are paired along the
airplane fuselage. [...]
The entry doors are translating, plug-type doors. During opening, the door first
moves inward and upward, then translates outward and forward.
(Boeing 747-400 FCOMv2 1.50.3 - Airplane General, Emergency Equipment, Doors, Windows - System Description, emphasis mine)
This will make accidental opening of these doors while the aircraft is pressurized impossible.
Based on the picture from the video it was the L2 door, right in front of the wing (L3 is the overwing exit):
(YouTube: Passenger deploys emergency slide on Rossiya Airlines 747)
The passenger who opened the door probably did not know about the ARM state of the door:
Passenger Entry Door 1, 2, 4, and 5 Slide/Raft Operation
When the door mode select lever is in ARM position and the door operating
handle is rotated 180 degrees, the door begins to open and the power assist
opening system activates.
The flight attendant must release the door operating handle and continue to assist
the door opening motion by using the handles on the door and on the door
surround panel until the door is in the full open and latched position. The
door-mounted escape slide/raft deploys and inflates. [...]
When the door is to be opened from the interior and slide deployment is not
desired, the door mode select lever must be in DISARM position.
(Boeing 747-400 FCOMv2 1.50.3 - Airplane General, Emergency Equipment, Doors, Windows - System Description)