The question needs context. You need to ask your friend for more clarification. Relative dates can be quite confusing. If your friend wanted to be more precise in his question, he could add "from today".
"Last two weeks from today" means the last 14 days. Whereas "The last two weeks" could have many meanings depending on context.
Consider this scenario.
Today is Friday, February the 3rd. I ask my friend "What are you doing this Sunday?" which would imply the next Sunday on the calendar (Feb 5). Or I could ask "What are you doing next Sunday", which could imply next week (Feb 12). Even though I asked about "next Sunday" it's not actually the next Sunday.
If somebody asked you "Where did you work last year?" they likely wouldn't mean literally all of 2016 or even the previous 365 days. There would likely be more context to it.
Consider this conversation.
Judy says
"Thanks for coming to visit me on my Birthday!", to which I
reply
"My pleasure! It was easy for me to get here because my new office is just around the corner."
"Where did you work last year?"
"On the other side of town."
Judy isn't asking me what my job has been for the last 365 days, she's asking me where I worked on her birthday last year.
It is a confusing topic that native English speakers still get confused about.
In your specific scenario, it wouldn't be rude to ask him "Do you mean this week and last?" or "Do you meant the last 14 days?" or "Do you mean last week and the week before?". I personally have found it common to ask for clarification of dates in casual conversation. Legal documents and conversation where it really matters would likely have explicit dates.
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.
Best Answer
An explicit copula (form of BE) is not necessary. The past participle forgotten here acts as an adjective, parallel with famous. Famous follows the noun it modifies because it is modified by a preposition phrase to its 'right', and forgotten comes after that because it is the second element in a conjoined modifier, famous ... but ... forgotten. If that PP in their day were replaced with once you could write
which would make the adjectival character of forgotten more obvious. But you are not obliged to write it that way; you could also write