SEF Advance encodes the URL and special characters become ,  etc. Firefox 3 decodes the URL so it's shown in the raw form, it's not how the search engines see them.

You can always use title alias or manual alias if you want to skip special characters.
SEF Advance doesn't strip special characters automatically because it is the only pure logic SEF solution for Joomla! / Mambo. This means it doesn't store URLs in database or anywhere else. This requires that no part of the URL is missing but also does that it is supreme in its performance since it never deals with issues with huge database tables, indexing issues, double entries, slow db connections etc.

There's a page on my site about the Podcast Suite that does this as well. And yes, I use SEF Advance.

As I explained in previous post, you can't completely skip the characters from the long title because of the nature of SEF Advance internal working, being a logic based and not database storage dependent SEF solution.

In the on-the-fly conversion the whole article title must be passed in URL in order for SEF Advance to retrieve the article id. If some parts of the title, like punctuation, would be missing from the URL, the program would not be able to find the article.
In a DB based solutions the URLs are saved in database automatically and then it doesn't matter how the URL looks like, it can be with stripped special chars, but then it comes with all performance drawbacks.

In SEF Advance there are 3 ways to avoid having encoded characters, aka strange chars in URL:

1) Put a replacement for a special character under "URL replace" in SEF Advance configurations.
In this example, since you use hyphen as word separator, the regular hyphens are URL encoded. To avoid that you could put something like "-=>_". This way all hyphens that occur in article titles will get replaced by underscores, thus avoiding hyphen shown as "Space Invader" in FF3. Of course, then you can't have underscores in your titles but they are less often occuring.

2) Use short URLs (title alias) setting.
Then you are required to always enter a short version of your article title with latin chars only. This is also the best option for non-latin sites like russian, chinese, arabic etc.

3) Define manual alias.
Whereever you notice strange URL you can manually enter the alias for that URL and it will be used instead. Of course, this solution is not automatic.