Video support used to require Rosetta, but they fixed that earlier this year by making the video support Apple Silicon native in 23.4 in June. So 23.5.1 should import videos directly; I just did it with an MP4 file on my M1.
Because video support is Apple Silicon native on Photoshop 23.4 and later, Rosetta is needed only for some installer components, but not Photoshop itself, and definitely no longer required for video import on Photoshop 23.5.1. If an .mp4 or .mov file isn’t importing, the cause is probably something other than Rosetta, although I’m not sure what it would be.
One possible reason is if Photoshop 23.4 or later was originally installed on an Intel Mac and migrated to an Apple Silicon Mac. In that case it might be missing proper Apple Silicon components, and that would be solved by uninstalling and reinstalling Photoshop on the M1. But if you installed Photoshop 23.4 or later directly on the M1, it should be fully Apple Silicon native, including video support.