Heya,
I found the video you were watching, and it said he was playing Chex Quest 3. This added a few features, and tried to improve consistency between levels.
The second shot is from the original Chex Quest version. The room just ends with the switch. In CQ3, in order to "explain" how you ended up in the Storage Area (E1M2) after Landing Zone (E1M1), they added a door. Just a subtle upgrade ^^