that "if" means exactly same to "when"?
I came across these sentences and that "if" after "And" seems like meaning exactly same to "when".

or there is any difference in meaning between the original sentence and the same sentence but replaced the if with a when?

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How about televisions? 20 years ago we were all peering at these tiny, cubical boxes, and now we’ve got High-Def, flat-screen, fully digital, massively sized televisions with more pixels than you can shake a stick at. And if we’re not at home when our favourite show is on, it’s not a problem – we just record it for later viewing. We accept this as normal today, but it was unheard of before 1999 .
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Thank you!

Question

that "if" means exactly same to "when"?
I came across these sentences and that "if" after "And" seems like meaning exactly same to "when".

or there is any difference in meaning between the original sentence and the same sentence but replaced the if with a when?

＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
How about televisions? 20 years ago we were all peering at these tiny, cubical boxes, and now we’ve got High-Def, flat-screen, fully digital, massively sized televisions with more pixels than you can shake a stick at. And if we’re not at home when our favourite show is on, it’s not a problem – we just record it for later viewing. We accept this as normal today, but it was unheard of before 1999 .
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊

Thank you!

Answer

Sure, in this sentence they would mean about the same thing.
.
When says it happens: it would be talking about a time.
If says it may happen: it would be talking about the circumstance, condition.
So in your sentence, they are about equivalent.
.
And, when the building falls over there will be mass devastation.
And, if the building falls over there will be mass devastation.
Again, sort of the same, but the first one doesn't really feel right as the whole building is not likely to fall over.

Answer

They are very very close to the same. 
"If you're not at home" implies slightly that there's a problem - not being at home - and recording is a solution. "When you're not at home" is a little more "ok, no problem, sometimes you watch, sometimes you record, either way."

But, that's only if I had to come up with a difference. If you just asked me to translate each separately, I'd probably treat them the same.

Answer

Hi Dadada,

It's good that you're thinking about how a combination of words can change the meaning.

To answer your question, 'when' would not be suitable to replace 'and if' because the writer seems to be using 'and' as a transition. 'If' is the beginning of a conditional sentence. The author could have said something like, "Also, if we're not at home..." 
I hope you find this helpful. :)

Answer

And if
Is not the same as
When
They are not interchangable.

In your example, the sentence would be exactly the same with "AND" omitted.

I've always been advised not to start sentences with the word AND.

If this happens = something may or may not happen
When this happens = something will definitely happen.

If and when is a phrase that means something is highly likely to happen, it's just a matter of time.

If and when the polar ice caps melt the sea levels will rise.

Answer

In your example, there is no difference in meaning. Note there is also an expression “if and when”. This can be used in a situation where it doesn’t sound right to use “when” because the likelihood of the event happening is low. “If and when the building falls over ...”