Here is what The Cambridge Grammar of English (p242) has to say on this issue:
When the copula is cliticised to the subject in informal style, many speakers use the third-person singular form irrespective of the number of the post-verbal NP. There's only two problems remaining. This pattern suggests the verb agreement is simply with there, treated as a 3rd person singular pronoun like it.
When the copula is pronounced as a full independent word, the person-number properties of the verb match those of the post-verbal NP ... .
So it appears that following the clicticised is in there's with a plural noun is not uncommon in informal language. It suggests that the TV presenter said: There's only two episodes left, not There is only two episodes left.
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