Answering this question over the long term is not possible since the idea of pubcasts is very new, but we can share the following information:

• /node/53 (Structural Evolution of the Protein-kinase Like Superfamily) was one of our first posts on July 19, 2007. As of October 7, 2007 (80 days) it had been accessed 39131 times, or almost 500 times per day. This does not mean that viewers watched the whole thing, but rather just accessed it.
  

When the video became available for this specific paper it led to a big spike of traffic on the PLoS Computational Biology Web site where the article was published. Again this spike does not necessarily imply the reader read the paper only accessed it, yet increased exposure was recorded.

• /node/1049 (Ten Simple Rules for Getting Published) has been watched 5489 times in 44 days or about 124 times per day and was filmed by the author simply sitting at their desk and using a webcam.
  
  
• /node/2755 (Adaptation to Human Populations Is Revealed by Within-Host Polymorphisms in HIV-1 and Hepatitis C Virus) has been watched 6047 times in 24 days or about 252 times per day.
  

These data would imply:

1. Many more people access your paper than would be the case if it just appeared on the publishers Web site and in PubMed.

2. For a paper that was published some time ago the pubcast creates renewed interest in the work.