http://www.speedrun.com/hl1 "¤ Demo submission is required to verify all runs. Even if you decide to record/stream the run you will still need to submit all demos from when the timer starts to when the timer stops. ¤ If you do not have video proof of the timer stopping you will need to include a screenshot of your final timer. Demo recording guide: http://www.speedrun.com/hl1/guide/m3lo4" You can zip your demos and upload them on Dropbox/Google Drive then link it in the description of your run.
A demo is a file that records a lot of things happening in the engine, like inputs, but once per map file. It's not a recording because you need the map files and also you need time to play each demo individually. Also you can cheat and do segmented runs instead of RTA runs by submitting demos.