Hmm - thats what was going on before. https://github.com/mozilla/nocturnal/pull/13/files#L15L54

After more investigation (a print statement) it looks like the scraping script is just not putting the 'B' on the end of the extension:
![sizes in mb](http://f.cl.ly/items/0x3e0o3q2z2L431m031J/Screen%20Shot%202013-04-03%20at%204.24.10%20PM.png)