You can copy and paste comments from one asset to another from within the media player.
Open up your options in the Detail panel and select Copy Comment.
Then open a new asset and from the same options you should now see Paste Comment selectable.
Once pasted, all the comments you originally selected will appear in this asset, including annotations and attachments.
Only visible comments, including filtered or searched, will be copied. Use the filter options to ensure the comments you want will copy over.
You can also copy and paste comments between any asset type, meaning it doesn’t have to be between video to video file, audio to audio, etc. If, for example, a video file is copied and pasted into an image file, the same metadata and timeline information will still appear, even though there is no timeline on an image.