Im new to speed running and im curious, I use livesplit and and how is time without loads timed? Can I use a video of a run I already have and cut it?

if you right click your splits > compare against > game time. you can also use the auto splitter to automatically split for you. go to edit splits and hit activate on the auto splitter

also no, you can't cut a run because people will think its spliced. you dont need to know the time without loads to submit though

For future runs: There are 2 ways to time without loads, and one is preferred over the other.

1. Do what FireNinja suggested (although I'm not sure if it's that simple since this game's one is dumber)
2. When you start a run, and whenever you die, when you load in type record [some demo name] in console. Type stop when the run ends (when you shoot the moon). This will give you a recording ONLY of in-game time (provided you start and end at the correct time) which you can time using the Portal 2 Demo Timers in resources. (If you're going to do option 2, I recommend also downloading sourcelivetimer and using that as your livesplit, but it's more limited than livesplit so it's up to you)

If you already have a run: You are allowed to go through the run and remove the load times manually. If you're off by a few seconds, it isn't a big deal until you're going for a competitive time. However, actually removing the load time in the video is unnecessary and just looks suspicious, so don't do that