I post a reply on the page you provided:
Chunking method is very important for using in Windows Azure Webapp.
Uploading a large file might cause out of disk space of a WebApp. So when we want to use WebApp for asp.net mvc uploading, we should chunk the large file to small parts, when a chunk is received, we upload it to Azure Storage immediately, then we can clear the space. After all chunks are uploaded, we merge them by calling Azure Storage API, then we can upload a very large file without out of disk space exception.