You are not able to use the Youtube platform on your Clamshell iBook any more? The Freeware Program MacTubes (min. MacOSX 10.4.2) searches the Youtube platform and displays a list of videos that match your keywords. Permform a download and play the MP4 video files using the VLC Player.
Perform a right click on an interesting video in the list (CTRL+Trackpadclick on your iBook) and download ist as MP4 (not FLV or HD). For a playback, use VLC Player 0.8.6i for PowerPC. Any Firewire-Clamshell iBook (with 8MB Video-RAM) will do the job.
MacTubes requires a G4 processor only for the internal playback of the listed videos. The G3 processor is way to slow to perform this playback.