You are using Adobe Reader 9 in the browser and notice that the Typewriter tool is not available in the More Tools dialog, even though it displayed in Reader 8 in the browser.
In Reader 8, the Typewriter tool displayed in the More Tools list but disappeared after a user selected it if the PDF did not have the appropriate rights. Because this function confused users, Adobe hid the option in Reader 9 in the browser until the PDF was given rights to use the Typewriter tool.
To use the Typewriter tool in Reader 9 on a PDF opened in the browser, enable this right on the PDF using Adobe Acrobat Professional.
To use the Typewriter tool in Reader standalone, enable the commenting right on the PDF using either Acrobat or Reader Extensions server.
For more details about enabling the Typewriter tool, see http://blogs.adobe.com/dmcmahon/?p=822.
After you enable the PDF to use the Typewriter tool with Acrobat, open it in the browser. The Typewriter toolbar automatically opens in the browser window. You also see the Typewriter tool entry in the More Tools dialog, as shown below:
The Typewriter tool is only supported for static PDF documents. It does not work with dynamic documents because it has the same limitations as standard comments in relation to dynamic documents.