The new (updated and hopefully stable) distribution of files is located at the bottom of this post.
New in this release:
1) Fixed a bug in which errors could possibly occur when two users simultaneously convert the same YouTube video. This has been addressed with an additional constant "_ENABLE_CONCURRENCY_CONTROL" in the config class, which toggles this feature on and off. The only code to change is in YouTubeToMp3Converter.class.php and config.class.php.
I will soon be updating the paid-for version of the app as well, and I will email an updated (free) copy to all those who have already purchased the script. (Updates will be sent to your Tradebit
email addresses only.)
As always, please let me know if you have any questions/concerns regarding the above and/or the code.