Here are the video results from the Bates Tech Balsa Wood Bridge Competition 2011. This simple video footage of the competition makes for a good learning opportunity. This video does not explain the rules very much, and it does not say whether they were going for total weight held or the highest efficiency score. However, it does have a variety of designs that are interesting to observe if you are looking to build a balsa wood bridge.
I like this video because it gives the weight of each bridge, a nice close up of the design, and then has a slow motion video of how the bridge failed. This gives you a much better picture of how to improve these designs.
The video description mentions that a new rule for this year allowed the use of cabling. This is interesting to note based on which bridge won the competition. Did you guess which bridge would hold the most beforehand?