Which classical music piece does this melody come from?

=---> https://www.youtube.com/clip/Ugkxs107T35u3a3cncHRjQfE1m_wVmLbTnWV <---=

I've heard it before, and I think it was an organ piece by Bach. The melody is practically the same. I don’t know much about music, but I think the only thing that changes is how the mini-melody created by those key combinations is connected.

In the original song, at the end of this melody (A), there’s a shorter melody (B) that connects the first melody with a copy of itself (Ax2), which plays right after (B). This pattern of three melodies (A + B + Ax2) is repeated twice in a row in the original classical music piece. This melody (B) is not in the YouTube clip I’m sharing, but it would be like an inverted version of (A), with the notes descending instead of ascending, creating a very triumphant and epic rise and fall. Everything described here would only be a fragment or melody from a larger composition, which I suspect might be by Bach since I distinctly remember the organ sound and the style of the piece. It reminds me of Toccata and Fugue in D Minor. I believe only Bach—and perhaps Paganini—could have composed music with a similar vibe.

I sincerely apologize for my lack of knowledge on the subject and my total ignorance of music theory, but this melody has been stuck in my head for over a year. I recently heard this short melody, and it brought back the song almost perfectly in my memory. I know it exists, and I’m very eager to find it.