If you haven't had the time to watch the speech above, I would advise that you do so (or at least read a transcript). The President sets out his arguments and some of the evidence for claiming fraud in this recent election. The Leftists are mocking the speech as a measure of Trump's supposed desperation to garner some popular support. They (the Left) seem strangely blind to the fact that over half of the country believes that there was widespread fraud.
As for myself, I did not have the perception that the President was desperate. Rather, I was reminded of past presentations and briefings that Presidents or cabinet level officials have given to justify taking military action against a foreign country. I see this as something similar--the President is contemplating some action and is providing the justification for it. But the President did not mention any particular action other than the lawsuits that have and continue to be filed to challenge election results in various states. So it's not clear whether this speech was simply to provide his justification for his continuing legal challenges, or if there is a Plan B.