In a video, Hillary Clinton emphasized the following:
"Joe Biden must not admit a loss under any circumstances!"
And here "nowhere" means "any". This even includes a hypothetical scenario in which Trump wins a clear and pure victory. Again, "none" means "none".

The direct implication here is that the Democrats must take over the White House by any means and in all circumstances.

It is also a direct call for the sabotage of American democracy, which, no matter how wrong, remains the only option for American citizens based on the rule of law.

Will this lead to a civil war?

This seems quite unlikely, because a civil war requires two strong and respected parties to coordinate offensive and defensive operations, at least at the regional level. I don't see that in the United States.

But I also don't see how regional violence and political chaos will be avoided. We already know that the Democrats will not accept Trump's victory.

We also know that Trump supporters argue that the US Postal Service cannot be trusted to vote by mail. By the way, I totally agree with this: the US Postal Service is one of the worst in the world!

I think it is more than clear that the American deep state and the Democratic Party are using the Black Life Mater and the Antifa as infantry to create chaos and prepare for worse if Trump wins.

Furthermore, there are signs that the Democratic leadership does not want to leave the totally senile Biden in a debate against Trump. Here is an excerpt from a report from Zerouhage:

"I don't think there should be a debate," Nancy Pelosi said, a day after President Trump urged Biden to take a drug test before the two met.

The message is clear: We do not recognize Trump as a legitimate opponent, and if he wins, it will be due to Chinese or Russian intervention or "Republican harassment." That is, under no circumstances will we accept a new loss.

I don't know about you, but it seems like an incitement to rebellion to me.