compression ratio vs processing power
compression ratio vs image quality
(some video codec algorithms have a lossless compression mode, but normally video streaming uses lossy compression to meet typical bandwidth constraints)

simple to implement
free from patents

designed for videoconferencing
encumbered by patents (manufacturers must pay licensing fees)

supported by Adobe Flash
derived from H.263 standard but is not compatible with it
encumbered by patents (manufacturers must pay licensing fees)

legacy codec, predecessor to VP6 and Theora
free from patents (On2 donated relevant patents to public)

supported by Adobe Flash
successor to VP3 codec
encumbered by patents (manufacturers must pay licensing fees)

derived from VP3 codec
free from patents

used for video on DVDs
encumbered by patents (manufacturers must pay licensing fees)

supported by Apple Quicktime
encumbered by patents (manufacturers must pay licensing fees)

supported by Adobe Flash and Apple iTunes
includes varient with lossless compression
very popular codec on platforms with sufficient power
encumbered by patents (manufacturers must pay licensing fees)

SIP (used for Voice-over-IP conferencing with video)
RTSP (often used with RTP as the data transport)

RTP
RTMP

HTTP/HTTPS (adds overhead but can be useful for firewall traversal)
network transport
receive stream
decoding
display