I have recently begun speedrunning Portal, and I am using the speedrun auto recorder from https://github.com/RedHaze/speedrun-demo-record-unified. Is there a way to combine the demos it puts out into 1 large demo?

Not sure what you mean by "demo", because your link leads to nowhere. If you are asking if it's possible to combine several videos to one video, most video editing softwares will let you do that.

@Oreo321 Delete the period from the end of the link. Demo is referring to a playback file which captures game inputs (think Quake).

I'm not familiar with the software or game at all, but looking at the OoB WR, combining these files may not be necessary. Consider asking on the game's forum or Discord.

Okay thank you. The link was meant to show what plugin I was using to record my Portal runs. I found out from another forum that most mods accept a compressed file with each demo individual demo piece.