Most likely they are using one of/combination of: After Effects, Premiere Pro, DaVinci Resolve, iMovie and/or Final Cut Pro as those are the more standard tools in the industry.
Then again, I just started using it. So far I'm pleasantly surprised at its UI. After using the detestable UI in GIMP (and the somewhat hokey-looking one in Audacity), I didn't expect much from open source.
Because it has a nice video editor in it, that's useful for lots of things.
Might be hard to get into if you never used Blender before. But if you've done 3D modelling in Blender, you'll be pleasantly surprised that your intuition of how to move, scale and generally edit stuff works the same in the video editor as in the rest of Blender.