TCP or UDP for streaming?

Generally, real-time connections like video streaming, VoIP, and some games will use UDP (User Datagram Protocol). UDP is used where real-time quick communication is crucial, and losing a few frames/packets in the process is acceptable.

Non-real time communication most often uses TCP (Transmission control Protocol) as it is well established, provides packet ordering, retransmissions, and prevents packet loss. TCP is used where transferring every frame/packet is important.
Netflix, Hulu, Youtube, etc. video streaming all use TCP and simply buffer a few seconds of content, instead of using UDP since the delay is not crucial and TCP transfers can be easily accomplished over HTTP and web browsers without the need for additional plugins and software.

Generally, if the content will be made available later, it is most likely using TCP.
Live TV streams and multicast video conferencing, on the other hand are usually over UDP. Such applications usually require their own protocol on top of UDP (often RTP/RTCP over UDP).