This is from October 16 but still relevant at least in general terms. It does run longer than most video clips I post, but I think it's worth your time, and much of it is pretty funny.
Oliver's main point is that third party candidates aren't necessarily an improvement over those offered up by the major parties, much as we'd like to hope otherwise. OK, they might have been better than Trump, but that's a low bar. As for Hillary Clinton, no matter how much you might dislike her, she's pretty clearly more knowledgeable than any of the third party candidates you're likely to have heard of.
On the other hand, there have certainly been quite good third party candidates in the past, a major example being Teddy Roosevelt when he ran as a Bull Moose. Teddy wasn't as great as some people remember him, but he was probably no worse than Woodrow Wilson, who won that election.
However, a good third-party candidate can actually make things worse, and not just by the spoiler effect. The structure of our Rube Goldberg system for electing presidents is such that should we ever have three truly competitive candidates, the election would very likely the thrown into the House of Representatives, where each state's delegation gets one vote. That's actually worse than the Electoral College. Until we eliminate this nonsense and switch to a direct vote, preferably with a runoff, any sensible independent candidate should seek the nomination of a major party, as both Bernie Sanders and Donald Trump did this year. Third party fans may contend that this isn't practical, claiming the party bosses won't allow it. But Sanders did pretty well, and Trump won the nomination, in both cases over the wishes of the parties in question. And certainly both Trump and Sanders attracted more interest to themselves and their proposals than they would have as third-party candidates.
I should note that Oliver's criticism of Jill Stein provoked predictable responses from her supporters. (Follow the link above to the YouTube page and look at the comments and the list of related videos.) The main objection was that Oliver misrepresented her views on vaccines, but that's not true. He objected only to her weakening her original pro-vaccine statement. At least one response objected to what Oliver said about her proposal to deal with student loan debt with quantitative easing. Critics correctly noted that she suggested other approaches as well. But in fact, the scale of student debt is so large that the most practical source of the necessary funds may well be to have the Fed buy up student loans as it did with bad mortgages. (Whether that's desirable or not is a separate question; I'm just talking about how it might be financed.) But that's actually a separate matter, since the problem Oliver was pointing out was that Stein claimed that the president had the authority to order the Fed to do that, and that's simply not true. Oliver's objection wasn't to her tackling student loan problem per se but to her lacking such a basic understanding of the Federal Reserve and the powers of the president.