Most testing platforms have this
built in. If you need a generic one and some tips on statistical significance, Avinash’s post here has good stuff: http://www.kaushik.net/avinash/excellent-analytics-tip1-statistical-significance/
Three must-read links on video
for conversion: http://conversionxl.com/how-to-use-video-to-increase-conversions/, and the case study data for eParty: http://www.internetretailer.com/2011/02/22/videos-boost-online-profile-eparty-unlimited and for Premiere Game Tables: http://blog.treepodia.com/2011/03/ecommerce-video-roi-a-case-study/. I also highly recommend http://wistia.com which we use at Moz for video.
Great post on case studies
and lessons learned: http://moz.com/blog/lessons-learned-from-21-case-studies-in-conversion-rate-optimization-10585