Hi,

 If i've understood you correct you can use this code where "file" is the path to your movie: 

UnifiedFile filePath = HostingEnvironment.VirtualPathProvider.GetFile(file) as UnifiedFile;
if (filePath == null) return;

Stream s = filePath.Open(FileMode.Open, FileAccess.Read);
int len = (int)s.Length;
byte[] buffer = new byte[s.Length];
s.Read(buffer, 0, len);
s.Close();
Response.Clear();
Response.AppendHeader("content-disposition", "attachment; filename=" + filePath.Name);
Response.BinaryWrite(buffer);
Response.End();
 

-Kjetil 

Beware of that this approach might cause some massive amount of memory to be allocated...consider for example sending a 1Gb videofile which would cause a 1Gb buffer to be allocated...

Now, all this is done for you in the EPiServer.Web.Hosting.WebDownloadManager which has a convenient method: TransmitFile.

You might call it like this:
EPiServer.Web.Hosting.WebDownloadManager,TransmitFile("/Documents/folder/folder/video.mov")

If the file is hosted on a nativeprovider, the fastes Response.TransmitFile can be used, if not, the file content is streamed in reasonably sized chunks.

It also sets the appropriate content headers for you if you specify the DownloadAction.Download
(i.e. content-disposition: attachment)

/johan