There was a recent post about Bento Boxes on NHK World. I've uploaded it to youtube and embedded it here.
It was originally aired October 24th, 2008 in Japan (though it looks like it's from the 90s...) and has been dubbed over in English in the recent release.
This is an interesting program about the history and use of bento, including:
- Development of bento boxes in 16th century and their increase in popularity in the 17th
- Wooden vs Plastic Bentos 曲げわっぱ
- Decoration (Sageju)
- E-Maki 蒔絵
- Bentos used in work, outings (hana-mi 花見), and celebrations