I ran demo recorder for my speedrun and don't have a video. How can I find the file and submit it as proof for my run?

Go into your Portal folder and there you should find folders that are named after the date and time each run started.

Get the demos out of the folder of your PB and put them together in a zip for uploading them to a file hoster of your choice.

If you used the vault save, don't forget to include the vault.dem in the zip of your demos.