I had a speedrun rejected, because my timer wasn't on. Of course you can just look at the time below the video (there is also ingame time), to show how long the run took. However my run was rejected nonetheless.

So my question is, are there general rules about this kind of thing (I suspect it happens from time to time), or is this purely handled on game to game basis?

And if there are general rules, where can I view them?