This is not a screencast but it is an important lecture about searches and search engines! It offers many examples of users' difficulties with searching. It is aimed people designing search systems but can be equally useful to inquisitive search engine users who wish to expand their set of searching strategies. It was delivered in 2005 so it's a bit out of date on  a few things but most of the important points still hold.

For those using the Portal to get their UEA news, you can get the latest from this web by following the same procedure as described in the following video for PG Oracle. All the important news feeds from this site are included. Thanks to CSED for recording this video.