Being that the subject heading of this thread is "Personal Protection," the handguns chosen for comparison, and their uses, should be noted. And while I understand that the purpose of this video was not to critique the handguns themselves, but instead the effectiveness of their respective rounds, it is worthwhile to consider the primary intended use of these handguns. Both the Beretta 92FS and the Ruger Secuity-Six are what I would consider full-sized handguns and not necessarily the best for purposes of concealed carry. However, I own a 92FS and have carried it in a shoulder holster; it definitely can be done, but it does print, letting the discerned know you're carrying. And while I do not own the Ruger Secuity-Six, I do have a N-frame, 6" .357 Mag--yes, a bit larger than the Ruger, but suffice it to say, both of these double-action-only pistols were intended to be hip-holstered weapons and not necessarily for concealed carry. Again, I understand that that was not the purpose of the video.
In nearly all instances, the ballistics of the .357 Mag will outperform that of 9mm, especially considering that the 9mm somewhat ceilings out (at least with what is widely available commercially) with 124gr projectiles, while the .357 Mag is widely available up to 158gr. But both can be quite effective, depending on shot placement. And that is another area not discussed in this video, but is nonetheless quite important given the two handguns chose for comparison. First, the Ruger is double-action, meaning that before the shot will go off, pulling of the trigger first sets the hammer back, before falling to ultimately strike the primer. Thus, and unless someone wants to "cowboy" it by setting the hammer back between each shot with either the thumb of the shooting hand, or the sweeping the opposite hand, it takes a bit more pulling on the trigger, and therefore requires more practice to accurately fire the Ruger.
The 92FS, while being a double-action on the first shot, will be single-action every shot thereafter (until the safety is set, which automatically drops the hammer). This leads to a pistol that at least has very good controllability and accuracy in follow-up shots, especially when under pressure.
To summarize, while the .357 Mag does have what most would consider superior ballistics compared to the 9mm, if one were to compare the two handguns used in the demonstration, what the 9mm round lacks in ballistics can be made up by the relatively easier-to-fire 92FS.
But, with all things, YMMV.