Hi Franki,
I’m not sure what the issue is in regards to Firefox. I haven’t seen this issue before. Either way, I’m releasing a new version of the plugin built on the latest version of the API, which should be far more stable and have a lot of new features.
I’m working on finishing up the plugin and putting together the website and documentation. Along with the free plugin will be some premium add ons for purchase such as front end user uploads, analytics and a few more.
The uploader should be a lot more stable in the next version as well.
If you’d like to keep up on notifications and such for the plugin, the site will be http://www.YouTubeforWordPress.com or http://www.yt4wp.com , it should be up this weekend when I have a chance to get the content and documentation up.
Thanks,
Evan