You do not need to include the {BUILDDATE} tag outside of the php code that displays the encoded adsense.

In the new adsense video the {BUILDDATE} tag is included in the footer - this is not required to make the adsense work.

To enable automating the inclusion of adsense after a set number of days you use the {BUILDDATE} tag within the php code and when the page is displayed in the browser the php code is run and essentially replaces itself with the script tags pointing to your adsense javascript file.

Steve