I couldn't do it with just quick saves alone so what I did for a minute, is spam quick save and quick load repeatedly till the up beat music plays then I would load and then spam quick saves while holding w. Idk it worked for me. As Sif_Rose said, bind your quick save and quick load to your mouse wheel as having it on the keybinds is really hard to spam fast enough for the glitch to work.

You can't splice or edit the videos so this wouldn't work. At all. It's a good speedrun and I enjoy it a lot. If you can't sit for the full thing do what Jugador said and just do the DLC...