Do you not think the expert in the linked video might have a point?
In my day, terrorist were civilians who blew up vehicles and buildings to use terror to get politics to change. The problem with countries proscribing other countries is that the proscribing gets caught up in making partisan alliances, which, we know from history, often leads to world wars.
Also, if you set completely objective criteria you might well find yourself having to proscribe a lot more countries than origiinally intended. And to be completely independent about all this, you should really have a neutral third party doing the proscribing - along the lines of a UN sort of entity.
If your know your history, alliances/proscribing type behaviour led to wwi and wwII, along similar lines. George Orwell wrote about this sort of thing in Homage to Catalonia, and Ponsonby in relation to wwI, they both also said that not everything in the media is necessarily true.
If you think the end justifies the means without limit and you think it is worth having armed conflict across the globe, then I can see why you might support it all without question. If not, as I said, i think the expert had a point.