After a speedrun I did, I realized I forgot to attach a timer to it. Is there any easy way to add one now because I don't really want to wait 3 and a half hours to just add it again (by just taking the video and like overlaying it).

You could probably just time it manually with frame by frame to see what second it falls on, because I assume you did it on youtube.

I know what time i got but in the rules it says: "You must display an external timer at all times."

Hence the question.

I use VSDC free video editor, it allows me to start a timer on the frame i want and end it on the frame i want as well. It goes up to 10 hrs of counting. To add the timer, go to editor > add object > text > counter. It is slow to export with the free version but that is the only downside for me.

thanks for the info!

it is okay to add a timer after - you can do so however you like most. We appreciate it since it makes timing much easier for everyone.