I recently downloaded several of the live training videos and have really enjoyed them! I bought Aperture 2 several years ago but its mainly been used as a place for the kids to offload their SD cards - effectively an underground silo now amounting to over 12,000 images.
Even though I've read the A3 user guide many times, the visual approach of your videos really brings things to life - for me, actually seeing it done is so much better than reading about it.
Keep up the great work!