There are a lot of ways to make website which allows users upload their videos
1.Upload file straight to specific folder
2.store the clip binary into the database
it depends on what programming language and database you use
if you use PHP and MySQL the second way is better
but if you use ASP and MSSQL I recommend first one, because MSSQL cost you much more money than MYSQL, if you use database.
and also there is open source software which does what you want to do what you need to search for it in Search engines or Open source softwares directories
good luck