Just watched a current video very negative on the current white house administration. Roughly equal likes vs dislikes. A Like could mean “I like what they are doing” OR 'I dislike the administration too so it’s good you have negative information." Same on Dislike. “I don’t like what they are doing” OR “Fake news”. I have a tendency to think Dislike means “I just don’t like the message”.
Not sure what interpretation you can make. The late night stuff that mocks Trump regularly gets exponentially more likes than dislikes (especially Colbert who can hit 30-40k). The alt-right have their space where they “trigger” liberals and get thousands of views and likes. The millennial left have their space where they hate on neoliberal corporate shills and right wingers. There’s content for everyone on youtube.
I would always read a Like as “I like what you posted”. So if the content is negative, a Like means you share the negative sentiment.