This post was published back in 2008. It may not function as originally intended or may be missing images.
Flash Sees Text Inside <b> Tag as Seperate Font and Must Be Embedded
In flash, if text inside html tags like <b> or <i> is not appearing in your dynamic textfields, you need to embed the stylized font. Flash/Actionscript sees the text inside as a seperate font and therefore it also needs to be embedded.
For example, if you have a dynamic textfield with Arial. If you add a bold tag (<b>) around text inside the field, you will need to additionally embed Arial with bold turned on into your flash document.
I ran into this while working on flash graphs for Tail Report.
I found the answer in the Los Angeles Flash Users Group (via Google)