Currently the policy is to accept only videos of the original run, not a replay. There was a discussion on the Necrodancer Discord about this some time ago.

The core reason is that a replay is only an unreliable reconstruction of the original run.

This creates a variety of specific problems, but the biggest one is: if you are running a low% category without video-recording your runs and get a PB, sometimes the replay will desync. Then you wouldn't be able to submit your PB even if replays were accepted. So to avoid randomly losing PBs, it's better to video record all your runs if you are running a category seriously.

A secondary reason is that the time reported at the end of a replay is just a number stored as text in the replay file. As such it is easy to modify. The replay timer is inaccurate anyway so detecting a small modification would be impossible.