Changing the speed of multiple clips simultaneously

1. Continue with 12-6.prproj and undo any speed changes.
2. Select all 3 video clips.
3. Right-click the clips --> choose Speed/Duration --> change Speed to 50% and click OK.
All 3 video clips play at 50% speed, but only the last clip expanded.
4. Press Ctrl+Z
5. Select all 3 video clips again.
6. Right-click the clips --> choose Speed/Duration --> change Speed to 50% and select the Ripple Edit, Shifting Trailing Clips --> click OK.
All 3 clips expand and play at 50% speed.

http://www.adobe.com/education/pdf/cib/prempro/prempro_cib_11.pdf
http://www.scribd.com/doc/5471953/Adobe-After-Effects-CS3-Professional-User-Guide
http://www.scribd.com/doc/7868547/Using-Adobe-After-Effects-CS4
http://www.photobus.co.uk/print/premierePro_tutorial.pdf