Seems like there is no way to delete the custom field 'enclosure' (if I delete it in a post, as soon as I press update it will appear again).
OK, but how can I remove the link to the video file (my-vide.flv), which is added automatically in the post? (this custom field adds it when a video is present in the post)
I have no code that would call this custom field.
Can't find anything on the internet about this. I just found a code to remove the direct link to the video (which allows downloads) from feeds, but not from the post itself.