The BrookTree is a video capture chip (as in for viewing TV) that is well supported by Linux and the BSDs. The brooktree chips come in many varieties, such as the Bt848 / 849 / 878 / 879. Once upon a time the datasheets were publically available for these chips, apparently, hence the good driver support in Linux and the BSDs.

In the BSD systems, you get BrookTree support by using the bktr(4)? driver, which is well documented in the man page. In Linux systems, you apparently get BrookTree support by using the bttv driver.

To watch video, you probably want to use a piece of software like xawtv. On the cards that have an FM tuner present, you can use xmradio to get the audio stream.