For the SpeedDial, follow the same instructions above, but open Database: %appdata%\Opera Software\Opera Stable\favorites.db and use the following SQL command:

SELECT "[" || name || "](**" || url || "**)" FROM favorites WHERE type=0

Also, if you have folders in your SpeedDial, try something like:

SELECT "<dt>" || a.name || "[" || b.name || "](**" || b.url || "**)</dt>" FROM favorites a, favorites b WHERE b.type = 0 AND b.parent_guid = a.guid

But in this case you'll have to manually edit the resulting html Bookmarks file to be able to import it to Firefox/Chrome. It's easy, just create headers for each folder in the html file.