Sure, it could be the Argentine sub. That was so obvious that it wasn't worth mentioning. It remains a possibility.
There are many other possibilities: a different submarine, SUB meaning SUBcontractor @Snowden, SUB meaning SUBject meaning an identified person, etc. There isn't enough info yet to determine which of these is the stronger candidate. And Q does use multiple meanings so just because one meaning might get proven does not rule out other meanings from being simultaneously true.
Not sure why you wasted 8+ hours on YT. The info moves so fast, here on the board, that personally I cannot stand listening to a TV person or a video because the information rate is tooo sloooooowww.