For anybody who has missed Tanel Poder's "Secret Hacking Session - about full scans, direct path reads, object level checkpoints, ORA-8103s" its now available under:
http://blip.tv/tanel-poder-oracle-troubleshooting-tv/oracle-troubleshooting-tv-show-season-1-episode-2-5459181
This show is really a must-see :-)