"would have v3" or "must have v3" for guessing about situations or things in the past

We were taught at school that condition 3 (would+have+v3) is used for unreal past, which means "there is no more chance for it to happen in the other way around" such as "if you had driven the car carefully, he would not have died". So, we can easily understand that "condition 3" is used there is no more opportunity for something to happen in another way because it already happened in the past. You can't reverse the time.

But today, I was watching ITV and the TV presenter, when he appeared after a break, said:

"If you were watching earlier, you would have heard me talk about the solution."

He simply referred to his previous talk about a solution before the break. And the break-time passed. So he appeared again and he continued talking on the same issue. So he wanted to remind the viewers that he was talking about this issue before the break time.

But I got confused when I heard him said ""if you were watching earlier, you would have heard me talk about the solution." He used conditional 3 (would have v3) which seemed irrelevant to the situation, as in this situation he is not referring to a past event which he now wishes to have happened in the opposite way.

What he is doing is to guess something did happen. So, the situation here is not a wish for past event, and it is only a guess or assumption about a past event.

So;

1. Why did TV presenter say "if you were......., you would have heard me..."? instead of "If you had watched ........"
2. Would it not have been better if he instead said "....you must have heard me...", not "would have heard" because he is guessing or assuming that something was highly likely the case. And "must" is the right word, for highly likelihood.
• I can't see what the problem is here. The conditional perfect (would have + past participle) describes something that might have happened in the past.The viewers might have been watching earlier, or perhaps not. Commented Jan 22, 2018 at 12:42
• The problem here is that TV presenter does not wish for a past event to have happened the opposite way. He is just guessing or presuming that something did happen in the past. This situation is the same as the one "when you see that the ground is wet and say "it must have rained", isn't it? Commented Jan 23, 2018 at 13:20
• The 3rd conditional is: "If you had been watching earlier you would have heard me talk about the solution" The viewer cannot go back in time to hear the presenter talking about the solution. The speaker in your case is suggesting that there are some viewers who may have just joined the show. The phrase uttered by the presenter is perfectly grammatical and is not ambiguous. Commented Nov 28, 2021 at 9:59
• The modal verbs will and would are also used for speculating something with certainty: (someone rings the doorbell) 1 A: Who's that? B: That'll be the postman. 2 A: Tim would've missed the beginning of the film if uncle Roger hadn't given him a lift" Commented Nov 28, 2021 at 22:25

The so called 3rd conditional would be the following:

If you had been watching earlier you would have heard me talk about the solution"

If + Past Perfect (and) Would/Wouldn't have + Past Participle

This means a viewer who was not watching before the commercial break cannot go back in time to hear the presenter talking about the solution.

The speaker in the OP's case is suggesting that there are some viewers who may have just joined the show, i.e after the commercial break.

If you were watching...

The phrase uttered by the presenter is perfectly grammatical (some English grammars call it mixed conditional) and is not ambiguous at all.

It was then, if you were listening closely, that you would have heard Will whisper ever so softly to Madeline, “Is it too soon to ask you to revisit Savannah with me, my dear?

• The original question clearly asked if the phrase was in the 3rd conditional, that has since been edited out. `2- Is this really conditional 3` Commented Nov 28, 2021 at 22:29
• but the word "earlier" expresses an past event, so that I think it should be "If you had been watching earlier" rather than"If you were watching earlier" Commented Mar 22, 2023 at 2:37
• @LEHANH I have explained as best as I could in the answer, I included the 3rd conditional form and explained its meaning. Of course what you say is possible, and if this were an English test for Intermediate level students, it would probably be considered the "correct" answer. But the original phrase is not ungrammatical, it is English and it makes sense. Commented Mar 22, 2023 at 8:32
• @LEHANH When I posted my answer it was answering a slightly different question which was edited soon after* See the comment I posted at the top. The OP removed the 2nd Q on Nov 28, 2021 at 21:12. Commented Mar 22, 2023 at 9:02