A live or pre-recorded audio and/or video session that uses the Internet as the broadcasting and distribution medium.

Audio and/or video data is compressed and packetized into a specific format, predetermined by client-side software, so it can be streamed over the Internet.
"I'll be doing a live webcast tonight on uStream, and then another one on BlogTV"
by Alfred_FL February 9, 2009
The art of twisting ones self up on a swing and masturbating then when you are ready to ejaculate let go of the ropes spreading ejaculatory matter like a web.
The floor is sticky from your webcasting.
by GottagoJo March 5, 2019