Euclid never made a conjecture about the infinitude of twin primes.
It is possible to guess that he was making a conjecture on the basis of his text but it requires wishful thinking.
Here is the paper where de Polignac makes his general conjecture (which if true also implies the twin prime conjecture).
Regarding the NOVA show, Goldston makes a comment to those behind the NOVA segment (with a response) here:

