Jesse posted a comment which is worth elevating to a blog post:
"Hey, read your VSTO C# book (all 1000 pages), and loved it--really helped jumpstart my current Word 2003 customization project. Anyhow, I checked out those videos, and they weren't really brimming with useful information. Two Microsoft papers credited to Andrew Whitechapel are extremely useful to people like me who use VSTO v2 and want to learn more about the design and use of VSTO v3:
VSTO 2005 SE Design (http://go.microsoft.com/?linkid=5467322)
VSTO 2005 SE Tutorials (http://go.microsoft.com/?linkid=5467323)
Both are linked to on the home and download pages for the current beta of VSTO v3. Hope everyone who reads here enjoys them too!"