What you don't see is the six other poor quality and sometimes actually spammy answers there. Granted its a video conversion question, and they attract spammers. You're not one. Awesome.
We've iterated reiterated and for that matter, even been berated over post quality, and well, its something that's essential considering the unusual scope of the site. As such, well, answers like this get deleted first, and often as quickly as possible
While we'd love to post a comment, go back, and delete later at some point, it makes much more sense for us to delete (and entirely unscientifically, as a mod on two sites, VERY few deleted posts get improved like this), comment (for the few, who like you go back and fix your posts) and get back to it later if the poster actually did something about it.
I don't entirely agree with Undo's wording (and we shall chat about that in private at some point), but yeah, you could either do as you did, fix up the answer (and post a custom flag explaining that the answer has been substantially improved and you'd like to have it reviewed), or to post a new answer substancially improving the new ones.
I've undeleted the answerand hope that you keep this incident in mind for future answers.
