I think it depends honestly. I can't comment on everyone here, but realistically, if you are in a high stress situation, chances are you won't be half as ticklish as these stories or videos make people out to be.
If anyone ever truly were kidnapped by someone malicious or held down against their will and violated at a party or any of these other themes, say fighting a war against aliens, being taken prisoner, and tickled senseless, chances are from the stress and adrenaline of the situation you will become much less ticklish. Again, can't comment on everyone but a few examples I have noticed before are myself, my wife, and women I have been with in the past.
While I don't have any high stress situations such as mentioned above, I have noticed that when my wife is really angry or pissed off or upset, her ticklishness basically becomes nonexistent. And I am not exaggerating when I say she is ticklish to the touch. She is probably one of the most ticklish women I have ever encountered basically everywhere, most ticklish spots being feet, underarms, and neck. But when she's pissed off or upset and I have tried tickling her before, doesn't work. Her emotions affect her ticklishness. I am essentially the same way. When I am in a bad mood, annoyed, don't feel like dealing with people, my ticklishness decreases a lot.
Another example which you can Google yourself is how people actually typically become less ticklish when tickled by strangers. There's actually a great video of an experiment of this they did on YouTube, where I believe people walk across a room holding something while being tickled by strangers and then by a significant other or loved one. Many of them were barely ticklish with the stranger, whereas the significant other/friend/family member tickling them in the same spot had them going crazy.
So, I guess I am bringing all this up because you could argue tickling is a weakness and possibly a good form of torture/interrogation, but I am just not seeing it in a realistic life situation or scenario, especially a war with anyone, including aliens where fear and anger would typically be the two dominant emotions in most people