Q:

Why is というのは used (both times) in this sentence?

I'm trying to understand the use of というのは in the second sentence below. Is it a way to refer to the 職業 in the first sentence? I find in some places that というのは can mean "the reason I'm saying this is..." Is that the meaning expressed in this example? For example, people are given a blue card (because) they have a useful profession?

その場面というのはどういった場面かというと、
  ナチスの兵士がですね、ユダヤ人を職業別で分けていきます。
  役に立つと見なされた職業というのはブルーカード、
  役に立たないと見なされた職業というのは即ゲットー行きです。

Translation from subtitles: "The scene I'm talking about is the one with the Nazi soldiers separating Jewish people by profession. They give a blue card to people who are considered with an useful job. People who are considered with an unuseful job are sent to the ghetto immediately." 
Source: https://www.youtube.com/watch?v=3xs-XWk_oQA
0:55

A:

というのは is a fixed phrase.

と: the quotative particle which is used with いう
いう: "say"
の: the nominalizer (turns a verb into a noun)
は: the topic marker

So literally, ○○というのは is something like "saying ○○ is ..."
というのは can be used in two ways.

というのは used alone at the beginning of a sentence is a conjunctional phrase, which means "I mean", "That is to say", "I'm saying this because", etc. In this case, と refers to what the speaker said in the previous sentence.
○○というのは is a fixed pattern used when the speaker wants to explain the characteristics of something, or to define something. You can think of it as a special emphatic topic marker. It's often interchangeable with ○○とは, which is another important particle combination used to give a definition.

人生というのは長い旅だ。 ≒ 人生とは長い旅だ。 ≒ Life is a long journey.

In your example, その場面というのはどういった場面か is basically the same as その場面はどういった場面か. And it forms a noun phrase (embedded question) which means "What kind of scene that scene is".

その場面というのはどういった場面かというと、
  ≒　「その場面はどういった場面か」というと、
  ≒ (lit.) When I say "what kind of scene that scene is", ...
  ≒ To explain that scene in details, ... / The scene I'm talking about is ...

(と)いうと after the embedded question here is another very common pattern which roughly means "To tell/say ...", "Speaking of...", etc.

本当のことを言うと、… To tell the truth, ...
なぜかと言うと、…　To explain why, ... / The reason why is ...
率直に言うと、… Frankly speaking, ... / To be honest, ...

