Use of imperfect tense to mean conditional

Question

I saw this used in some celebrity interview and in a tv show I'm watching. Basically, the imperfect tense is used interchangeably with the conditional tense to mean a conditional statement.

My questions are: How do you know when you can use this? Can you always answer a hypothetical question with the imperfect tense?

The examples I've heard:

(Jugando a casar, matar o follar) Le preguntaron ¿qué harías? y él contesta:

Yo me casaría con Bella, a esta la mataba y con esta me casaba (See video)

That was the first time I heard of it so I didn't think much of it but then I saw it again in Vis a vis:

Les preguntaron a las presas ¿qué harías si salieras de aquí mañana? y todas contestaron con el condicional, salvo una, la Rizos, que dijo:

Me pegaba un baño en bolas en el mar

Answer 1

It is always safer to use the conditional:

• Si pudiera elegir, me casaría con ésta. (present counterfactual)

The imperfect past sounds colloquial and is not always safe to use:

• Si pudiera elegir, me casaba con ésta. (present counterfactual)

In this book reference can be found to this use of the tense, known as "pretérito imperfecto hipotético o condicional":

Its use in the condition is only accepted when it is also used in the result. In this case, the sentence will be understood as past counterfactual:

• Si sabía, venía antes (I I'd known, I would've come earlier).