How can I access the webcam easily with VS2010 and C#?
I tried to copy the avicap21.dll, but VS2010 can't import the library.
This is a native DLL. not a COM object so VS will not import it for you. You need to write your own "header" translation or find something on the web:
(this is a translation for a later version) http://www.c-sharpcorner.com/UploadFile/yougerthen/810262008070218AM/8.aspx
Also you should consider using DirectShow which is a more .NET friendly way to access WebCams.
E.