On the video it looks like the L1 slide didn't deploy.
This one reason why the regulation requires to do the evacuation test with only 50% of the available exits. This is why we have cross-aisles at every large emergency exit. It is expected, that not all doors are available, for whatever reason. Not ideal, but normal and expected. You can not check the slides prior to every flight, and if you would test them regularly, it would tell you nothing because you have to re-pack after.