<p>Is there any one website which contains many good C# screencasts?</p>

dnrTV
dnrTv is a fusion of a training video
  and an interview show. Training videos
  are typically sterile and one-way.
  Let's face it, you can only take so
  much. But you need to see the code! In
  this format, you get the spontaneity
  of an interview talk show, and the
  detail of a webcast or training video.
Carl Franklin is the host of the
  wildly popular mp3 talk show .NET
  Rocks!, which he started recording in
  August, 2002. dnrTV launched on
  January 12th, 2006, the same week as
  .NET Rocks! show number 159!
We see dnrTV as a natural adjunct to
  .NET Rocks!, allowing more technical
  topics to be explored in detail. As
  always, Carl keeps the atmosphere
  light and conversational, which makes
  for a nice way to spend your lunch
  hour!