I am watching your old WC videos, while trying out for myself. Half way into video no. 3, in EditDeveloper, your error routine for missing or wrong data, calls a javascript function called attachErrorLink, however I can't find this function in any of the files which are shipped with wc5.64. This is from the created html when I leave txtName blank:
<td><span style="font-weight:Normal">Please correct the following</span><hr><ul><li><a href="javascript:;" onclick="attachErrorLink('txtName')">Name cannot be left empty</a></li>