We were tickled, too, when we realized Cedar was pulling the string. Willow looks pretty curious in the movie, though she was scared of the bee at first. She didnt like the noise the string made (very screechy kinda noise--it's wearing out), so she kept her distance from the bee. I think Cedar's clear obsession with it peeked Willow's curiousity enough, though, to overcome her nervousness. If Cedar ever gave her a chance, it'd be interesting to see if Willow gave the string a pull.
Cedar (tri), Willow (blen), & Holly (ruby)