“Didn’t work” isn’t really a good description.

How did you try to embed a video? Did you read the documentation?

What did you expect it to do?

ARVE does nothing with iframe embeds codes if they are pasted into a posts text editor as they are.

ARVE also does nothing at all whatsoever to your posts content when you delete the plugin so looks like you are fast in blaming but have actually no idea what you are doing.

What are “iframe body tags”? There are iframe and body tags that are not related to each other are are two totally different tags. ARVE builds a chunk of HTML with a iframe tag inside it but it will ne longer generated from URLs on their own line for hosts WP does not support or [arve] shortcodes if you deinstall the plugin. I am not sure what you mean by “iframe body tags are completely empty” but ARVE will not change any of your pre existing tags.

Its actually impossible to guess what you actully did. But I seems like you are not interested in any help about it.