Although Star Trek has always been progressive for its time, with a good number of message episodes related to contemporary politics, it was off air for long enough that these people now making videos viewed the old trek as kids, when they weren't aware enough to know contemporary politics, and if watching something like TOS, the issues were mostly 'solved(at least in the minds of these kinds of viewers)'. If you give them the benefit of the doubt that their kid selves viewed these old shows apolitically, whats left is a show about a futuristic military vessel that as often as not has to solve issues with force. Its not too hard to see why Fascists could find value in that.