If you know a bit about linux you can go with a LAMP system. This is the basic Linux Apache Mysql PHP configuration.
You will need to edit configuration files by hand via the linux shell.
If you are a novice I would suggest a system with a controlcenter like Plesk, Cpanel, etc
This way you can set everything up via a webinterface and is much easier (but you pay a bit more for the license)
However if you are going to run a tube site you will also need to setup ffmpeg to encode your video's, and you will probably want to run apache & lighttpd side by side on a unique ip each. This way you can have apache run the php webpages (dynamic content) and have lighttpd do the video streaming. The big advantage of lighttpd over apache is that it supports resuming (and thus you can skip in a video). Apache itself cannot do this and your viewers will be frustrated that they cant skip forward in video's.
Personally I would go with the LAMP dedicated and choose for a Debian system. This is because I am very fluent in debian and I HATE rpm based distributions like centos, mandrake, redhat, etc. Then I would setup ffmpeg & lighttpd on a 2nd IP address to get everything running.
Shameless plug: We also sell mainly VPS server but can also do dedicated servers (pricing on request) and are willing to help you setup your tube site;
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