You can easily edit .dav files and save them as a .mp4 video using the Wondershare UniConverter. The tool supports more than 1000 file formats. Moreover, you can crop, trim, and cut the files. Additionally, it can remove audio from the video. The method is as follows:
Launch the tool and click on the Video Editor option.
Add the .dav file and apply the editing feature.
Click on the Cog button and select MP4 as the output format.
Hit Save to finalize the settings.