May defended her failure to set out additional details, even though the policy is blamed for reducing the Conservatives' lead in the polls in the past fortnight.
It follows the Conservative leader's refusal to take part in a seven-way debate on Wednesday.
The Labour leader has openly called for an end to Trident, the UK's nuclear weapons program, but has been forced to agree with its renewal after losing an internal party debate.
Foreign Secretary Boris Johnson hit out at Corbyn later, saying: "There is no point in having a nuclear weapon unless you are willing in principle to deploy it".
"It's not going to happen quickly, it's not going to happen easily, but we have to have that wish".
The 85-second montage of Corbyn's quotes has been circulating online for the last week and has been viewed 5.3m times, three times more than any other political campaign video.
We are entering "get the vote out" territory. The Labour leader said: "I'm very sorry this is not a debate, this is a series of questions".
Ryan went on to seemingly throw in the towel to the Conservatives nationally, saying: "The polls are all saying that the Conservative Party will win a large majority, possibly with more MPs than they have ever had before". It is subtitled: "On June 9th, this man could be Prime Minister. But this is an important moment for our country, we've got to get it right", she said.
"You'd have Diane Abbott who can't add up sitting around the cabinet table, John McDonnell who's a Marxist, Nicola Sturgeon who wants to break our country up, and Tim Farron who wants to take us back into the European Union, the direct opposite of what the people want".
"I'm afraid there is a lesson here about Jeremy Corbyn's psychology and his politics and his naivety, with which he approaches not just the logic of the nuclear deterrent but also the Brexit negotiations".
"We've been open about that, and I've also been open that there will be some hard choices to be made in addressing those various challenges".
Mrs May then faced more heath care questions when confronted by mental health patients who told her they had lost benefits due to failing Work Capability Assessments.
But she told a nurse who said her salary hasn't changed since 2009: "There isn't a magic money tree that we can shake that suddenly provides for everything that people want".
Mr Corbyn said Labour was "not looking to do deals with anybody" when asked if he would seek the support of the SNP.
ICM boss Martin Boon said: "A lot of polls showing a much narrower gap depend on whether you think young people and 2015 non-voters will actually turn out to vote on this occasion".
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