It is possible to watch streaming youtube on the clamshell 466. This is what i have, so this is what i tested it on.
First--Use the Opera browser. I tried them all. Opera is by far the best with video. Shrink the content of the page to 70 or 80%. You can change the size of the content by clicking view or command + or -.
Then just add &fmt=5 to the end of the video address. This forces the video to play at a lower quality that slow processors can handle. This can be done easily by right clicking on the video you want to watch, copy link address, paste in address bar enter &fmt=5, press enter and now you are watching youtube on a clamshell.