Timothy Murphy wrote:
I just bought a Google Chromecast but haven't tried it yet.
(It came with no instructions whatever.)

Should have been brief (but that's all you need) instructions in the box ...

1) install the chromecast app (I used the android version, I believe you
can do this step on an iOS or Windows device too).

2) Plug dongle into HDMI port.

3) Plug USB power into dongle (I bet HDMI spec now wishes it had
supplied 5V power).

4) Run the app which detects the dongle

5) Push settings (name, wifi details) to the dongle, possibly wait for
dongle to update its firmware and restart.

I'm not clear if this could be use in the same way as a set-top box?

Not really the same, you don't "use" the dongle as a device in its own
right, you just treat it as an alternate output for other devices.

On android, make sure you've updated apps such as iPlayer and YouTube to
latest versions, they should gain a "cast" icon, which toggles whether
they play media locally, or to the dongle.

Works nicely for what it does, YMMV especially if trying to access UK
content when not in the Uk.