just as we can't know for sure a scholar plagiarised a work unless he admits to it.
I don't think you have a clue what plagiarism means. People have been sacked, suspended, sued and convicted, expelled, etc without they admitting anything. Thats both in academia and the elsewhere.
Yours is not even a long stretch of the bow. You are not even in the zone. Plagiarism is either wholesale copying of content may it be a short paragraph, a picture or ideas or substantial copying of a body of work or even a framework.
The lady herself has indicated in her blog that the movie has inspired her. However creative one is, they will still use things that others have created along the way. The final product is an assembly of ideas and content. Notice the ceiling shot, the sun shining at a low angle with one half of the faces in shadow etc. All that too are copied. You consider that plagiarising? I have seen that done many times in films long before she left school.
Was this Ad's striking feature the snore and the dog. Was the snore and the dog a copy in form and content. Was the fart with the dog or the dog with the snore and it goes on and on.
Maybe you want to list the striking points of the Ad. Here is my take.
1) loss of life
2) unusual eulogy by spuse
3) Mrs Lee with a sari ? until you see the photo of the husband
4) So many friends
5) Intermarriage,mixed blood kids
6) Accepting imperfection in all including your loved ones (main message)
Looks like you are looking for all the imperfections even when they are not there.
Compare that with the NDP example that you cited on your blog and its different as chalk and cheese. The NDP is an obvious case of plagiarism.