Good point, and you are certainly correct to bring that up.
I suppose if using some regex to scrape the HTML of YouTube's public
pages is a crime, then my script is guilty as charged. (*Trying not to roll my eyes at corporate bureaucracy*)
So the conclusion that I draw here is that, if you use my app in production, on the internet and/or for commercial gain, you'll need to get the explicit written consent/authorization of YouTube first.
In lieu of that, I presume that YouTube authorizes use of it's own API to gain access to its videos repository: http://www.youtube.com/dev
. (This is something that I just discovered 5 minutes ago, actually, and substantiates my proposed use of such an API for future versions of my code, as suggested in my original post...)
One can only hope that the large number of sites out there that advertise YouTube video-to-mp3 audio file conversion are using this API. Only YouTube knows for sure, if they even bother to check.
Nevertheless, thanks again for adding this disclaimer regarding use of my app here and for those that similarly endeavor to piggyback YouTube's web services in general.