Learn English – No longer ago than yesterday

My opinion is yesterday is largely considered both. If today is December 9, yesterday i.e. December 8 does include day and night. Because until midnight, we did not change the date.

Yes, I agree with Caroffrey on her sentence. If you 'extended' the stay, merely saying it '...spend the night as well' conveys the message. But then be sure that you have mentioned yesterday before in that case.

But then, here are my two cents-

If you want to refer to a day, you call it 'yesterday'. But if you are talking about 'night', you call it yesterday night 'last night'.

So, if you spent the night, you say - "Last night, I was at my cousin's place."

For me the text "in the last two weeks" means not more than two weeks. I might write "in just over two weeks" to indicate a small number of days more than two weeks but less than three weeks. For the purpose in the question I might write "I have uploaded 5 videos in just over two weeks". All the other forms I can think of take more words to qualify the "two weeks" to indicate a few days more than two weeks.

Using the text "in the last three weeks" means not more than three weeks and so matches the ideas wanted by the question.