The version used in the onyesha is the "Saeed & Palash Remix". It has been released on multiple releases of "At The End". The song is 9:38 dakika long.
"The Scumfrog Remix" is the version that has been used in the megamix on the soundtrack release for season 3. That version has received quite a bit zaidi play in klabu and is considered kwa many to be the best remix of the song, even at the time when it came out, which is why I guess it was used instead. Either that au it might be due to licensing issues which is why several songs had different versions featured on the various soundtrack releases of the show.
I've embedded a video of the remix below. Feel free to compare it to the scene in the onyesha which I'll link here:
link They edited a bit for the onyesha though.