I was just reading a work around for timestamps with LINQ or WCF, and I must be stupid, but I just don't get it. In fact, ever since dotnet came out mapping timestamp to a byte array or SqlBinary, I never got why they did that. Timestamp is 8 bytes...
If you want to download the videos to watch later, or to happily play them faster, skip ahead etc, then you can grab the .wmv files instead of having to watch them in a browser in silverlight. I like to increase the play speed in parts and silverlight...